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Columbia  SHitibcrsitu  ILccturcs 


THE  DOCTEINE  OF  EYOLUTIOX 

TPIE   HEWITT  LECTURES 

1906-1907 


COLUMBIA   UNIVERSITY  PRESS 
SALES   AGENTS 

NEW   YORK: 

LEMCKE   &   BUECHXER 
30-32  West  27th  Strbkt 

LONDON : 

HUMPHREY   MILFORD 

Amek  Corner,  E.G. 


COLUMBIA    UNIVERSITY  LECTURES 


THE  DOCTRINE  OF  EVOLUTION 


ITS   BASIS  AND   ITS   SCOPE 


BY 


HENRY   EDWARD    CRAMPTON,  Ph.D. 

PROFESSOR    OF   ZOOLOGY,    COLUMBIA    UNFVtRSITY 


COLUMBIA   UNIVERSITY    PRESS 

1916 


All  rights  reserved 


COPTBIGHT,   1911, 

By  the  COLUMBIA  UNIVERSITY  PRESa 


Set  up  and  electrotyped.     Published  June,  1911. 
Reprinted  December,  1912;  September,  1916. 


Notfaoolr  50re8B 

J.  8.  Gushing  Co.  —  Berwick  «fe  Smith  Co. 

Norwood,  Mass.,  U.S.A. 


u 


a 


\>^ 


PREFACE 


The  present  volume  consists  of  a  series  of  eight 
addresses  delivered  as  the  Hewitt  Lectures  of  Columbia 
University  at  Cooper  Union  in  New  York  City  during 
the  months  of  February  and  March,  1907.  The  purpose 
of  these  lectures  was  to  describe  in  concise  outline  the 
Doctrine  of  Evolution,  its  basis  in  the  facts  of  natural 
history,  and  its  wide  and  universal  scope.  They  fall 
naturally  into  two  groups.  Those  of  the  first  part  deal 
with  matters  of  definition,  with  the  essential  character- 
istics of  living  things,  and,  at  greater  length,  with  the 
evidences  of  organic  evolution.  The  lectures  of  the 
second  group  take  up  the  various  aspects  of  human 
evolution  as  a  special  instance  of  the  general  organic 
process.  In  this  latter  part  of  the  series,  the  subject 
of  physical  evolution  is  first  considered,  and  this  is 
followed  by  an  analysis  of  human  mental  evolution; 
the  chapter  on  social  evolution  extends  the  funda- 
mental principles  to  a  field  which  is  not  usually  con- 
sidered by  biologists,  and  its  purpose  is  to  demonstrate 
the  efficiency  of  the  genetic  method  in  this  department 
as  in  all  others;  finally,  the  principles  are  extended 
to  what  is  called  'Hhe  higher  human  life/'  the  realm, 
namely,  of  ethical,  religious,  and  theological  ideas  and 
ideals. 

Naturally,  so  broad  a  survey  of  knowledge  could  not 
include  any  extensive  array  of  specific  details  in  any 

V 

CK^A.0  PROPERTY  LIBRARY 

N.  C  State  College 


vi  PREFACE 

one  of  its  divisions;  it  was  possible  only  to  set  forth 
some  of  the  more  striking  and  significant  facts  which 
would  demonstrate  the  nature  and  meaning  of  that 
department  from  which  they  were  selected.  The 
illustrations  were  usually  made  concrete  through  the 
use  of  photographs,  which  must  naturally  be  lacking  in 
the  present  volume.  In  preparing  the  addresses  for 
publication,  the  verbal  form  of  each  evening's  dis- 
cussion has  been  somewhat  changed,  but  there  has  been 
no  substantial  alteration  of  the  subjects  actually  dis- 
cussed. 

The  choice  of  materials  and  the  mode  of  their  pre- 
sentations were  determined  by  the  general  purpose 
of  the  whole  course.  The  audiences  were  made  up 
almost  exclusively  of  mature  persons  of  cultivated 
minds,  but  who  were  on  the  whole  quite  unfamiliar 
with  the  technical  facts  of  natural  history.  It  was 
necessary  to  disregard  most  of  the  problematical  ele- 
ments of  the  doctrine  so  as  to  bring  out  only  the  basic 
and  thoroughly  substantiated  principles  of  evolution. 
The  course  was,  in  a  word,  a  simple  message  to  the  un- 
scientific ;  and  while  it  may  seem  at  first  that  the  dis- 
cussions of  the  latter  chapters  lead  to  somewhat  insecure 
positions,  it  should  be  remembered  that  their  purpose 
was  to  bring  forward  the  proof  that  even  the  so-called 
higher  elements  of  human  Ufe  are  subject  to  classifica- 
tion and  analysis,  like  the  facts  of  the  lower  organic 
world. 

It  may  seem  that  the  biologist  is  straying  beyond  his 
subject  when  he  undertakes  to  extend  the  principles  of 
organic  evolution  to  those  possessions  of  mankind  that 
seem  to  be  unique.     The  task  was  undertaken  in  the 


PREFACE  vii 

Hewitt  Lectures  because  the  writer  holds  the  deeply 
grounded  conviction  that  evolution  has  been  continuous 
throughout,  and  that  the  study  of  lower  organic  forms 
where  laws  reveal  themselves  in  more  fundamental 
simplicity  must  lead  the  investigator  to  employ  and 
apply  those  laws  in  the  study  of  the  highest  natural 
phenomena  that  can  be  found.  Another  motive  was 
equally  strong.  Too  frequently  m.en  of  science  are 
accused  of  restricting  the  apphcation  of  their  results  to 
their  own  particular  fields  of  inquiry.  As  individuals 
they  use  their  knowledge  for  the  development  of  world 
conceptions,  which  they  are  usually  reluctant  to  dis- 
play before  the  world.  It  is  because  I  beheve  that 
the  accusation  is  often  only  too  well  merited  that  I 
have  endeavored  to  show  as  well  as  circumstances 
permit  how  universal  is  the  scope  of  the  doctrine  based 
upon  the  facts  of  biology,  and  how  supreme  are  its 
practical  and  dynamic  values. 

It  remains  only  to  state  that  the  present  volume 
contains  nothing  new,  either  in  fact  or  in  principle; 
the  particular  form  and  mode  of  presenting  the  evolu- 
tionary history  of  nature  may  be  considered  as  the 
author's  personal  contribution  to  the  subject.  Nothing 
has  been  stated  that  has  not  the  sanction  of  high  author- 
ity as  well  as  of  the  writer's  own  conviction ;  but  it 
will  be  clear  that  the  believers  in  the  truth  of  the  analysis 
as  made  in  the  later  chapters  may  become  progressively 
fewer,  as  the  various  aspects  of  human  life  and  of  human 
nature  are  severally  treated.  Nevertheless,  I  believe 
that  this  volume  presents  a  consistent  reasonable  view 
that  will  not  be  essentially  different  from  the  con- 
ceptions of  all  men  of  science  who  beheve  in  evolution. 


CONTENTS 

OHAPTEE  PAGB 

I.    Evolution.     The  Living  Organism  and  its  Natu- 
ral History 1 

II.    The  Structure  and  Development  of   Animals   as 

Evidence  of  Evolution 35 

in.     The  Evidence  of  Fossil  Remains      .        .        .        .73 

IV.    Evolution  as  a  Natural  Process     ....  loO 

V.     The  Physical  Evolution  of   the    Human   Species 

and  of  Human  Races 150 

VI.     The  Mental  Evolution  of  Man        .        .        .        .107 

VII.    Social  Evolution  as  a  Biological  Process    .        .  241 

VIII.     Evolution  and  the  Higher  Human  Life         .        .  278 

Index 313 


IX 


EVOLUTION.      THE    LIVING   ORGANISM   AND    ITS   NATURAL 

HISTORY 

The  Doctrine  of  Evolution  is  a  body  of  principles 
and  facts  concerning  the  present  condition  and  past 
history  of  the  living  and  lifeless  things  that  make  uj) 
the  universe.  It  teaches  that  natural  processes  have 
gone  on  in  the  earlier  ages  of  the  world  as  they  do  to-day, 
and  that  natural  forces  have  ordered  the  production 
of  all  things  about  which  we  know. 

It  is  difficult  to  find  the  right  words  with  which  to 
begin  the  discussion  of  so  vast  a  subject.  As  a  general 
statement  the  doctrine  is  perhaps  the  simplest  formula 
of  natural  science,  although  the  facts  and  processes 
which  it  summarizes  are  the  most  complex  that  the 
human  intellect  can  contemplate.  Nothing  in  natural 
history  seems  to  be  surer  than  evolution,  and  yet  the 
final  solution  of  evolutionary  problems  defies  the  most 
subtle  skill  of  the  trained  analyst  of  nature's  order. 
No  single  human  mind  can  contain  all  the  facts  of  a 
single  small  department  of  natural  science,  nor  can  one 
mind  comprehend  fully  the  relations  of  all  the  various 
departments  of  knowledge,  but  nevertheless  evohition 
seems  to  describe  the  history  of  all  facts  and  their 
relations  throughout  the  entire  field  of  knowledge. 
Were  it  possible  for  a  man  to  live  a  hundred  years,  ho 
could  only  begin  the  exploration  of  the  vast  domains 

B  1 


If.  i 


2  DOCTRINE  OF  EVOLUTION 

of  science,  and  were  his  life  prolonged  indefinitely,  his 
task  would  remain  forever  unaccomplished,  for  prog- 
ress in  any  direction  would  bring  him  inevitably  to 
newer  and  still  unexplored  regions  of  thought. 

Therefore  it  would  seem  that  we  are  attempting  an 
impossible  task  when  we  undertake  in  the  brief  time 
before  us  the  study  of  this  universal  principle  and  its 
fundamental  concepts  and  applications.  But  are  the 
difficulties  insuperable?  Truly  our  efforts  would  be 
foredoomed  to  failure  were  it  not  that  the  materials 
of  knowledge  are  grouped  in  classes  and  departments 
which  may  be  illustrated  by  a  few  representative  data. 
And  it  is  also  true  that  every  one  has  thought  more  or 
less  widely  and  deeply  about  human  nature,  about  the 
living  world  to  which  we  belong,  and  about  the  cir- 
cumstances that  control  our  own  lives  and  those  of 
our  fellow  creatures.  Many  times  we  withdraw  from 
the  world  of  strenuous  endeavor  to  think  about  the 
'^meaning  of  things,"  and  upon  the  ^^why"  and  ^there- 
fore" of  existence  itself.  Every  one  possesses  already 
a  fund  of  information  that  can  be  directly  utilized 
during  the  coming  discussions ;  for  if  evolution  is  true 
as  a  universal  principle,  then  it  is  as  natural  and  every- 
day a  matter  as  nature  and  existence  themselves,  and 
its  materials  must  include  the  facts  of  daily  life  and 
observation. 

Although  the  doctrine  of  evolution  was  stated  in 
very  nearly  its  present  form  more  than  a  century  ago, 
much  misunderstanding  still  exists  as  to  its  exact  mean- 
ing and  nature  and  value ;  and  it  is  one  of  the  primary 
objects  of  these  discussions  to  do  away  with  certain 
current  errors  of  judgment  about  it.    It  is  often  sup- 


THE  LIVING  ORGANISM  3 

posed  to  be  a  remote  and  recondite  subject,  intelligible 
only  to  the  technical  expert  in  knowledge,  and  apart 
from  the  everyday  world  of  life.  It  is  more  often 
conceived  as  a  metaphysical  and  philosophical  system, 
something  antagonistic  to  the  deep-rooted  religious 
instincts  and  the  theological  beliefs  of  mankind.  Truly 
all  the  facts  of  knowledge  are  the  materials  of  science, 
but  science  is  not  met  physics  or  philosophy  or  belief, 
even  though  the  student  who  employs  scientific  method 
is  inevitably  brought  to  consider  problems  belonging  to 
these  diverse  fields  of  thought.  A  study  of  nervous 
mechanism  and  organic  structure  leads  to  the  philo- 
sophical problem  of  the  freedom  of  the  will ;  questions 
as  to  the  evolution  of  mind  and  the  way  mind  and  matter 
are  related  force  the  investigator  to  consider  the  problem 
of  immortality.  But  these  and  similar  subjects  in  the 
field  of  extra-science  are  beyond  its  sphere  for  the  very 
good  reason  that  scientific  method,  which  we  are  to 
define  shortly,  cannot  be  employed  for  their  solution. 
Evolution  is  a  science;  it  is  a  description  of  nature's 
order,  and  its  materials  are  facts  only.  In  method  and 
content  it  is  the  very  science  of  sciences,  describing 
all  and  holding  true  throughout  each  one. 

The  overwhelming  importance  of  knowing  about 
natural  laws  and  universal  principles  is  not  often  real- 
ized. What  have  we  to  do  with  evolution  and  science  ? 
Are  we  not  too  busy  with  the  ordering  of  our  immediate 
affairs  to  concern  ourselves  with  such  remote  matters  ? 
So  it  may  appear  to  many,  who  think  that  the  study 
of  life  and  its  origin,  and  of  the  vital  facts  about  plants 
and  animals  may  be  interesting  and  may  possess  a 
certain    intellectual    value,    but    nothing    more.     The 


4  DOCTRINE  OF  EVOLUTION 

investigation  of  man  and  of  men  and  of  human  life  is 
regarded  by  the  majority  as  a  mere  cultural  exercise 
which  has  no  further  result  than  the  recording  of  present 
facts  and  past  histories ;  but  it  is  far  otherwise.  Science 
and  evolution  must  deal  with  mere  details  about  the 
world  at  large,  and  with  human  ideals  and  with  life 
and  conduct;  and  while  their  purpose  is  to  describe 
how  nature  works  now  and  how  it  has  progressed  in 
the  past,  their  fullest  value  is  reahzed  in  the  sure  guid- 
ance they  provide  for  our  lives.  This  cannot  be  clear 
until  we  reach  the  later  portions  of  our  subject,  but 
even  at  the  outset  we  must  recognize  that  knowledge 
of  the  great  rules  of  nature's  game,  in  which  we  must 
play  our  parts,  is  the  most  valuable  intellectual  posses- 
sion we  can  obtain.  If  man  and  his  place  in  nature, 
his  mind  and  social  obligations,  become  intelligible,  if 
right  and  wrong,  good  and  evil,  and  duty  come  to  have 
more  definite  and  assignable  values  through  an  under- 
standing of  the  results  of  science,  then  hfe  may  be  fuller 
and  richer,  better  and  more  effective,  in  direct  pro- 
portion to  this  understanding  of  the  harmony  of  the 
universe. 

And  so  we  must  approach  the  study  of  the  several 
divisions  of  our  subject  in  this  frame  of  mind.  We 
must  meet  many  difficulties,  of  which  the  chief  one  is 
perhaps  our  own  human  nature.  For  we  as  men  are 
involved,  and  it  is  hard  indeed  to  take  an  impersonal 
point  of  view,  —  to  put  aside  all  thoughts  of  the  conse- 
quences to  us  of  evolution,  if  it  is  true.  Yet  emotion 
and  purely  human  interest  are  disturbing  elements  in 
intellectual  development  which  hamper  the  efforts  of 
reason  to  form  assured  conceptions.     We  must  dis- 


THE  LIVING   ORGANISM  5 

regard  for  the  time  those  insistent  questions  as  to 
higher  human  nature,  even  though  we  must  inevitably 
consider  them  at  the  last.  Indeed,  all  the  human 
problems  must  be  put  aside  until  we  have  prepared  the 
way  for  their  study  by  learning  what  evolution  means, 
what  a  living  organism  is,  and  how  sure  is  the  evidence 
of  organic  transformation.  When  we  know  what 
nature  is  Uke  and  what  natural  processes  are,  then  we 
may  take  up  the  questions  of  supreme  and  deep  con- 
cern about  our  own  human  lives. 


Human  curiosity  has  ever  demanded  answers  to  ques- 
tions about  the  world  and  its  make-up.  The  primi- 
tive savage  was  concerned  primarily  with  the  everyday 
work  of  seeking  food  and  building  huts  and  carrying  on 
warfare,  and  yet  even  he  found  time  to  classify  the 
objects  of  his  world  and  to  construct  some  theory  about 
the  powers  that  made  them.  His  attainments  may 
seem  crude  and  childish  to-day,  but  they  were  the 
beginnings  of  classified  knowledge,  which  advanced 
or  stood  still  as  men  found  more  or  less  time  for  obser- 
vation and  thought.  Freed  from  the  strife  of  primeval 
and  medieval  life,  more  and  more  observers  and  thinkers 
have  enlarged  the  boundaries  and  developed  the  terri- 
tory of  the  known.  The  history  of  human  thought 
itself  demonstrates  an  evolution  which  began  with  the 
savages'  vague  interpretation  of  the  'Svhat"  and  the 
^^why"  of  the  universe,  and  culminates  in  the  science 
of  to-dav. 

What,  now,  is  a  science?  To  many  people  the  word 
denotes   something  cold   and   unfeeling   and   rigid,  or 


6  DOCTRINE  OF  EVOLUTION 

something  that  is  somehow  apart  from  daily  life  and 
antagonistic  to  freedom  of  thought.  But  this  is  far 
from  being  true.  Karl  Pearson  defines  science  as 
organized  knowledge,  and  Huxley  calls  it  organized 
common  sense.  These  definitions  mean  the  same  thing. 
They  mean  that  in  order  to  know  anything  that  de- 
serves confidence,  in  order  to  obtain  a  real  result,  it 
is  necessary  in  the  first  place  to  establish  the  reality 
of  facts  and  to  discriminate  between  the  true,  the  not 
so  sure,  the  merely  possible,  and  the  false.  Having 
accurate  and  verified  data,  scientific  method  then 
proceeds  to  classify  them,  and  this  is  the  organizing 
of  knowledge.  The  final  process  involves  a  summary 
of  the  facts  and  their  relations  by  some  simple  ex- 
pression or  formula.  A  good  illustration  of  a  scientific 
principle  is  the  natural  law  of  gravitation.  It  states 
simply  that  two  bodies  of  matter  attract  one  another 
directly  in  proportion  to  their  mass,  and  inversely  in 
proportion  to  the  square  of  the  distance  between  them. 
In  this  concise  rule  are  described  the  relations  which 
have  been  actually  determined  for  masses  of  varying 
sizes  and  at  different  distances  apart,  —  for  snowflakes 
falling  to  the  earth,  for  the  avalanche  on  the  mountain 
slope,  and  for  the  planets  of  the  solar  system,  moving 
in  celestial  coordination. 

Such  a  principle  as  the  law  of  gravitation,  like  evolu- 
tion, is  true  if  the  basic  facts  are  true,  if  they  are  reason- 
ably related,  and  if  the  conclusion  is  drawn  reasonably 
from  them.  It  is  true  for  all  persons  who  possess 
normal  minds,  and  this  is  why  Huxley  speaks  of  science 
as  '^common  sense,"  —  that  is,  something  which  is  a 
reasonable  and  sensible  part  of  the  mental  make-up  of 


THE  LIVING   ORGANISM  7 

thinking  persons  that  they  can  hold  in  common.  The 
form  and  method  of  science  are  fully  set  forth  by  these 
definitions,  and  the  purpose  also  is  clearly  revealed. 
For  the  results  of  investigation  are  not  merely  forniulte 
which  summarize  experience  as  so  much  ''conceptual 
shorthand/'  as  Karl  Pearson  puts  it,  but  they  must 
serve  also  to  describe  what  will  probably  be  the  orderly 
workings  of  nature  as  future  experience  unfolds. 
Human  endeavor  based  upon  a  knowledge  of  scientific 
principles  must  be  far  more  reliable  than  where  it  is 
guided  by  mere  intuition  or  unreasoned  belief,  which  may 
or  may  not  harmonize  with  the  everyday  world  laws. 
Just  as  the  law  of  gravitation  based  upon  past  experience 
provides  the  bridge  builder  and  the  architect  with  a 
statement  of  conditions  to  be  met,  so  we  shall  find  that 
the  principles  of  evolution  demonstrate  the  best  means 
of  meeting  the  circumstances  of  life. 

Evolution  has  developed,  like  all  sciences,  as  the 
method  we  have  described  has  been  employed.  Al- 
chemy became  chemistry  when  the  so-called  facts  of 
the  medievalist  were  scrutinized  and  the  false  were 
discarded.  Astrology  was  reorganized  into  astronomy 
when  real  facts  about  the  planets  and  stars  were 
separated  from  the  belief  that  human  fives  were  in- 
fluenced by  the  heavenly  bodies.  Likewise  the  science 
of  life  has  undergone  far-reaching  changes  in  coming 
down  to  its  present  form.  All  the  principles  of  these 
sciences  are  complete  only  in  so  far  as  they  sum  up  in 
the  best  way  the  whole  range  of  facts  that  they  describe. 
They  cannot  be  final  until  all  that  can  bo  known  is 
known,  —  until  the  end  of  all  knowledge  and  of  time. 
It  is  because  he  feels  so  sure  of  what  has  been  gained 


8  DOCTRINE  OF  EVOLUTION 

that  the  man  of  science  seems  to  the  unscientific  to 
claim  finahty  for  his  results.  He  himself  is  the  first  to 
point  out  that  dogmatism  is  unjustified  when  its  asser- 
tions are  not  so  thoroughly  grounded  in  reasonable  fact 
as  to  render  their  contrary  unthinkable.  He  seeks  only 
for  truth,  realizing  that  new  discoveries  must  oblige 
him  to  amend  his  statement  of  the  laws  of  nature  with 
every  decade.  But  the  great  bulk  of  knowledge  con- 
cerning life  and  living  forms  is  so  sure  that  science 
asserts,  with  a  decision  often  mistaken  for  dogmatism, 
that  evolution  is  a  real  natural  process. 


The  conception  of  evolution  in  its  turn  now  de- 
mands a  definite  description.  How  are  we  to  regard  the 
material  things  of  the  earth?  Are  they  permanent 
and  unchanged  since  the  beginning  of  time,  un- 
changing and  unchangeable  at  the  present?  We  do 
not  need  Herbert  Spencer's  elaborate  demonstration 
that  this  is  unthinkable,  for  we  all  know  from  daily 
experience  that  things  do  change  and  that  nothing  is 
immutable.  Did  things  have  a  finite  beginning,  and 
have  they  been  ^^made"  by  some  supernatural  force 
or  forces,  personified  or  impersonal,  different  from  those 
agencies  which  we  may  see  in  operation  at  the  present 
time?  So  says  the  doctrine  of  special  creation. 
Finally,  we  may  ask  if  things  have  changed  as  they 
now  change  under  the  influence  of  what  we  call  the 
natural  laws  of  the  present,  and  which  if  they  operated  in 
the  past  would  bring  the  world  and  all  that  is  therein 
to  be  just  what  we  find  now.  This  is  the  teaching  of 
the  doctrine  of  evolution.     It  is  a  simple  brief  state- 


THE  LIVING   ORGANISM  9 

ment  of  natural  order.  And  because  it  has  followed 
the  method  of  common  sense,  science  asserts  that 
changes  have  taken  place,  that  they  are  now  taking 
place,  and  furthermore  that  it  is  unnecessary  to  appeal 
to  other  than  everyday  processes  for  an  explanation 
of  the  present  order  of  things. 

Wherever  we  look  we  see  evidence  of  nature's  change ; 
every  rain  that  falls  washes  the  earth  from  the  hills 
and  mountains  into  the  valleys  and  into  the  streams 
to  be  transported  somewhere  else;  every  wind  that 
blows  produces  its  small  or  greater  effect  upon  the  face 
of  the  earth ;  the  beating  of  the  ocean's  waves  upon 
the  shore,  the  sweep  of  the  great  tides,  —  these,  too, 
have  their  transforming  power.  The  geologists  tell  us 
that  such  natural  forces  have  remodeled  and  recast  the 
various  areas  of  the  earth  and  that  they  account  for  the 
present  structure  of  its  surface.  These  men  of  science 
and  the  astronomers  and  the  p>hysicists  tell  us  that  in 
some  early  age  the  world  was  not  a  solid  globe,  with 
continents  and  oceans  on  its  surface,  as  now ;  that  it 
was  so  very  hot  as  to  be  semi-fluid  or  semi-solid  in  con- 
sistency. They  tell  us  that  before  this  time  it  was  still 
more  fluid,  and  even  a  mass  of  fiery  vapors.  The  earth's 
molten  bulk  was  part  of  a  mass  which  was  still  more  vast, 
and  which  included  portions  which  have  since  condensed 
to  form  the  other  bodies  of  the  solar  system,  —  Mars 
and  Jupiter  and  Venus  and  the  rest, — while  the  sun 
remains  as  the  still  fiery  central  core  of  the  former 
nebulous  materials,  which  have  undergone  a  natural 
history  of  change  to  become  the  solar  system.  The 
whole  sweep  of  events  included  in  this  long  history  is 
called  cosmic  evolution ;  it  is  the  greater  and  more  inclu- 


10  DOCTRINE  OF   EVOLUTION 

sive  process  comprising  all  the  transformations  which 
can  be  observed  now  and  which  have  occurred  in  the 
past. 

At  a  certain  time  in  the  earth's  history,  after  the  hard 
outer  crust  had  been  formed,  it  became  possible  for 
living  materials  to  arise  and  for  simple  primitive 
creatures  to  exist.  Thus  began  the  process  of  organic 
evolution  —  the  natural  history  of  living  things  —  with 
which  we  are  concerned  in  this  and  later  addresses. 
Organic  evolution  is  thus  a  part  of  the  greater  cosmic 
process.  As  such  it  does  not  deal  with  the  origin  of 
life,  but  it  begins  with  life,  and  concerns  itself  with  the 
evolution  of  living  things.  And  while  the  investigator 
is  inevitably  brought  to  consider  the  fundamental 
question  as  to  the  way  the  first  life  began,  as  a  student 
of  organic  forms  he  takes  life  for  granted  and  studies 
only  the  relationships  and  characteristics  of  animals 
and  plants,  and  their  origins. 

.But  even  as  a  preliminary  definition,  the  statement 
that  organic  evolution  means  natural  change  does 
not  satisfy  us.  We  need  a  fuller  statement  of  what  it 
is  and  what  it  involves,  and  I  think  that  it  would  be 
best  to  begin,  not  with  the  human  being  in  which  we 
are  so  directly  interested,  nor  even  with  one  of  the 
lower  creatures,  but  with  something,  as  an  analogy, 
which  will  make  it  possible  for  us  to  understand  im- 
mediately what  is  meant  by  the  evolution  of  a  man, 
or  of  a  horse,  or  of  an  oak  tree.  The  first  steam  loco- 
motive that  we  know  about,  like  that  of  Stephenson,  was 
a  crude  mechanism  with  a  primitive  boiler  and  steam- 
chest  and  drive-wheels,  and  as  a  whole  it  had  but  a  low 
degree  of  efficiency  measured  by  our  modern  standard ; 


THE   LIVING  ORGiVNISM  11 

but  as  time  went  on  inventive  genius  changed  one  little 
part  after  another  until  greater  and  greater  efficiency 
was  obtained,  and  at  the  present  time  we  find  many 
varied  products  of  locomotive  evolution.  The  great 
freight  locomotive  of  the  transcontinental  lines,  the 
swift  engine  of  the  express  trains,  the  little  coughing 
switch  engine  of  the  railroad  yards,  and  the  now  extinct 
type  that  used  to  run  so  recently  on  the  elevated  rail- 
roads, are  all  in  atrue  sense  the  descendantsof  a  connnon 
ancestor,  namely  the  locomotive  of  Stephenson.  Each 
one  has  evolved  by  transformations  of  its  various  parts, 
and  in  its  evolution  it  has  become  adapted  or  fitted  to 
peculiar  circumstances.  We  do  not  expect  the  freight 
locomotive  with  its  eight  or  ten  powerful  drive-wheels  to 
carry  the  light  loads  of  suburban  traffic,  nor  do  we  expect 
to  see  a  little  switch  engine  attempt  to  draw  'Hhe  Twen- 
tieth Century  Limited"  to  Chicago.  In  the  evolution, 
then,  of  modern  locomotives,  differences  have  come 
about,  even  though  the  common  ancestor  is  one  single 
type ;  and  these  differences  have  an  adaptive  value  to 
certain  specific  conditions.  A  second  illustration  will 
be  useful.  Fulton's  steamboat  of  just  a  century  ago 
was  in  a  certain  true  sense  the  ancestor  of  the  '^Lusi- 
tania, "  with  its  deep  keel  and  screw  propellers,  of  the 
side- wheel  steamship  for  river  and  harbor  traffic  like 
the  ^^Priscilla,"  of  the  stern-wheel  flat-bottom  boats  of 
the  Mississippi,  and  of  the  battleship,  and  the  tug  l)oat. 
As  in  the  first  instance,  we  know  that  each  modern  type 
has  developed  through  the  accumulation  of  cbsOnges, 
which  changes  are  likewise  adjustments  to  ililTorent 
conditions.  The  diversity  of  modern  types  of  steam- 
ships   may    be    attributed    therefore    to    adaptation. 


12  DOCTRINE  OF  EVOLUTION 

The  several  kinds  are  no  more  interchangeable  than  are 
the  different  forms  of  locomotives  that  we  have  men- 
tioned. The  flat-bottom  boat  of  the  Mississippi  would 
not  venture  to  cross  the  Atlantic  Ocean  in  winter,  nor 
would  the  ''Lusitania"  attempt  to  plow  a  way  up 
the  shallow  mud-banked  Mississippi.  These  products 
of  mechanical  development  are  not  efficient  unless  they 
run  under  the  circumstances  which  have  controlled 
their  construction,  unless  they  are  fitted  or  adapted  to 
the  conditions  under  which  they  must  operate. 

Evolution,  then,  means  descent  with  adaptive  modifica- 
tion. We  must  examine  the  various  kinds  of  living 
creatures  everywhere  to  see  if  they,  like  the  machines, 
exhibit  in  their  make-up  similar  elements  which  indicate 
their  common  ancestry  in  an  earlier  age,  and  if  we  can 
interpret  their  differences  as  the  results  of  modifica- 
tions which  fit  them  to  occupy  different  place  in  nature. 

Two  objections  to  the  employment  of  these  analogies 
will  present  themselves  at  once.  The  definition  may  be 
all  very  well  as  far  as  the  machines  are  concerned,  but, 
it  may  be  asked,  should  a  living  thing  Hke  a  horse  or  a 
dog  be  compared  with  the  steamship  or  the  locomotive  ? 
Can  we  look  upon  the  living  thing  as  a  mechanism  in 
the  proper  sense  of  the  word  ?  A  second  objection  will 
be  that  human  invention  and  ingenuity  have  controlled 
the  evolution  of  the  steamship  and  engine  by  the  per- 
fection of  newer  and  more  efficient  parts.  It  is  certainly 
true  that  organic  evolution  cannot  be  controlled  in  the 
same  way  by  men,  and  that  science  has  not  yet  found 
out  what  all  the  factors  are.  And  yet  we  are  going  to 
learn  in  a  later  discussion  that  nature's  method  of  trans- 
forming organisms  in  the  course  of  evolution  is  strikingly 


THE  LIVING  ORGANISM  13 

similar  to  the  human  process  of  trial  and  error  which 
has  brought  the  diverse  modern  mechanisnis  to  their 
present  conditions  of  efficiency.  This  matter,  however, 
must  remain  for  the  time  just  as  it  stands.  The  first 
objection,  namely,  that  an  organism  ought  not  to  be 
viewed  as  a  machine,  is  one  that  we  must  meet  immedi- 
ately, because  it  is  necessary  at  the  very  outset  to  gain 
a  clear  idea  of  the  essentially  mechanical  nature  of 
living  things  and  of  their  relations  to  the  conditions 
under  which  they  live.  It  is  only  when  we  have  such 
a  clear  understanding  that  we  can  profitably  pursue 
the  further  inquiries  into  the  evidence  of  evolution. 
Our  first  real  task,  therefore,  is  an  inquiry  into  certain 
fundamental  questions  about  life  and  living  things,  upon 
which  we  shall  build  as  we  proceed. 


All  living  things  possess  three  general  properties  which 
seem  to  be  unique ;  these  are  a  peculiar  chemical  con- 
stitution, the  power  of  repairing  themselves  as  their 
tissues  wear  out,  and  the  abihty  to  grow  and  multiply. 
The  third  property  is  so  familiar  that  we  fail  to  see  how 
sharply  it  distinguishes  the  creatures  of  the  organic 
world.  To  realize  this  we  have  only  to  imagine  how 
strange  it  would  seem  if  locomotives  and  steamships 
detached  small  portions  of  themselves  which  could 
grow  into  the  full  forms  of  the  parent  mechanisms. 
Equally  distinctive  is  the  marvelous  natural  power 
which  enables  an  animal  to  re-build  its  tissues  a.s  they 
are  continually  used  up  in  the  processes  of  living  ;  for  no 
man-made,  self-sustaining  mechanism  has  ever  been 
perfected.    The  property  of  chemical  composition  is  be- 


14  DOCTRINE  OF  EVOLUTION 

lieved  by  science  to  be  the  basis  of  the  second  and  the 
third ;  but  this  matter  of  chemical  constitution  must  take 
its  proper  place  in  the  series  of  structural  characters, 
which  we  shall  discuss  further  on  as  we  develop  the 
conception  of  organic  mechanism. 

Whatever  definition  we  may  employ  for  a  machine 
or  an  engine,  we  cannot  exclude  the  hving  organism 
from  its  scope.  As  a  ''device  for  transforming  and 
utiUzing  energy"  the  living  organism  differs  not  at  all 
from  any  ''dead"  machine,  however  complex  or  simple. 
The  greatest  lesson  of  physiological  science  is  that  the 
operations  of  the  different  parts  of  the  living  thing,  as 
well  as  of  the  whole  organism  itself,  are  mechanical; 
that  is,  they  are  the  same  under  similar  circumstances. 
The  living  creature  secures  fresh  supplies  of  matter  and 
energy  from  the  environment  outside  of  itself ;  these 
provide  the  fuel  and  power  for  the  performance  of  the 
various  tasks  demanded  of  an  efficient  living  thing, 
and  they  are  the  sources  upon  which  the  organism 
draws  when  it  rebuilds  its  wasted  tissues  and  replenishes 
its  energies.  The  vital  tasks  of  all  organisms  must  be 
considered  in  due  course,  but  at  first  it  is  necessary  to 
justify  our  analogies  by  analyzing  the  structural  char- 
acteristics of  animals  and  plants,  just  as  we  might 
study  locomotives  in  a  mechanical  museum  before  we 
should  see  how  they  work  upon  the  rails. 

Among  the  familiar  facts  which  science  reveals  in  a 
new  light  are  the  peculiarly  definite  qualities  of  living 
things  as  regards  size  and  form.  There  is  no  general 
agreement  in  these  matters  among  the  things  of  the 
inorganic  world.  Water  is  water,  whether  it  is  a  drop 
or  the  Pacific  Ocean;  stone  is  stone,  whether  it  is  a 


THE  LIVING   ORGANISM  16 

pebble,  a  granite  block,  or  a  solid  peak  of  the  Rocky 
Mountains.  It  is  true  that  there  is  a  considerable  ran^e 
in  size  between  the  microscopic  bacterium  at  one  ex- 
treme and  the  elephant  or  whale  at  the  other,  but  this 
is  far  less  extensive  than  in  the  case  of  lifeless  things 
like  water  and  stone.  In  physical  respects,  water  may 
be  a  fluid,  or  a  gas  in  the  form  of  steam,  or  a  solid,  as  a 
crystal  of  snow  or  a  block  of  ice.  But  the  essential 
materials  of  living  things  agree  throughout  the  entire 
range  of  plant  and  animal  forms  in  having  a  jellylike 
consistency. 

But  by  far  the  most  striking  and  important  character- 
istic of  living  things  is  their  definite  and  restricted 
chemical  composition.  Out  of  the  eighty  and  more 
chemical  elements  known  to  science,  the  essential 
substance  of  living  creatures  is  formed  by  only  six  to 
twelve.  These  are  the  simple  and  obvious  character- 
istics of  living  things  which  are  denoted  by  the  word 
^^organic."  Everyone  has  a  general  idea  of  what  this 
expression  signifies,  but  it  is  important  to  realize  that 
it  means,  in  exact  scientific  terms,  —  constituted  in 
definite  and  peculiar  ways. 

The  living  thing,  then,  possesses  a  definite  constitu- 
tion, which  is  a  mechanical  characteristic,  while  further- 
more it  is  related  to  its  surroundings  hi  a  hard  and 
fast  way.  Just  as  locomotives  are  different  in  structure 
so  that  they  may  operate  successfully  under  dilTerent 
conditions,  so  the  definite  characteristics  of  living  things 
are  exactly  what  they  should  be  in  order  that  organ- 
isms may  be  adjusted  or  fitted  into  the  i^lares  in  nature 
which  they  occupy.  This  universal  relation  to  the  en- 
vironment is  called  adaptation.     It  is  only  too  obvious 


16  DOCTRINE  OF  EVOLUTION 

when  our  attention  is  dii'ected  to  it,  but  it  is  something 
which  may  have  escaped  our  notice  because  it  is  so 
natural  and  universal.  The  trunk  of  a  tree  bears  the 
limbs  and  branches  and  leaves  above  the  ground,  while 
the  roots  run  out  into  the  surrounding  soil  from  the 
foot  of  the  trunk;  they  do  not  grow  up  into  the  air. 
An  animal  walks  upon  its  legs,  the  wings  of  a  bird  are 
just  where  they  should  be  in  order  that  they  may  be  use- 
ful as  organs  of  flight.  And  these  mechanical  adjust- 
ments in  the  case  of  living  creatures  occur  for  the  same 
reason  as  in  mechanisms  like  the  steamship,  which  has 
the  propeller  at  its  hinder  end  and  not  elsewhere,  and 
which  bears  its  masts  erect  instead  of  in  any  other  way. 
The  next  step  in  the  analysis  of  organisms  reveals  the 
same  wonderful  though  familiar  characteristics.  The 
living  organism  is  composed  of  parts  which  are  called 
organs,  and  these  differ  from  one  another  in  structural 
and  functional  respects.  Each  of  them  performs  a 
special  task  which  the  others  do  not,  and  each  differen- 
tiated organ  does  its  part  to  make  the  whole  creature  an 
efficient  mechanism.  The  leg  of  the  frog  is  an  organ 
of  locomotion,  the  heart  is  a  device  for  pumping  blood, 
the  stomach  accomplishes  digestion,  while  the  brain  and 
nerves  keep  the  parts  working  in  harmony  and  also 
provide  for  the  proper  relation  of  the  whole  creature  to 
its  environment.  So  rigidly  are  these  organs  special- 
ized in  structure  and  in  function  that  they  cannot  re- 
place one  another,  any  more  than  the  drive  wheels  of 
the  locomotive  could  replace  the  smokestack,  or  the 
boiler  be  interchanged  with  either  of  these.  All  of  the 
organs  are  thus  fitted  or  adjusted  to  a  particular  place 
in  the  body  where  they  may  most  efficiently  perform 


THE  LIVING   ORGANISM  17 

their  duties.  Each  organ  therefore  occupies  a  particular 
place  in  an  organic  environment,  so  to  speak.  Thus  tlie 
principle  of  adaptation  holds  true  for  the  organs  wliich 
constitute  an  organism,  as  well  as  for  organisms  them- 
selves in  their  relations  to  their  surroundings. 

The  various  organs  of  living  things  are  grouped  so 
as  to  form  the  several  organic  systems.  There  are 
eight  of  these,  and  each  performs  a  group  of  related  tasLs 
which  are  necessary  for  complete  life.  The  alimentary 
system  concerns  itself  with  three  things :  it  gets  food 
into  the  body,  or  ingests;  it  transforms  the  insoluble 
foods  by  the  intricate  chemical  processes  of  digestion ; 
and  it  absorbs  or  takes  into  itself  the  transformed  food 
substances,  which  are  then  passed  on  to  the  other  parts 
of  the  body.  It  is  hardly  necessary  to  point  out  that 
the  ingestive  structures  for  taking  food  and  prejxiring 
it  mechanically  lie  at  and  near  the  mouth,  while  the 
digesting  parts,  like  the  stomach,  come  next,  because 
chemical  transformation  is  the  next  thing  to  be  done ; 
while  finally  the  absorbing  portions  of  the  tract,  or  the 
intestines,  come  last.  The  second  group  of  organs,  like 
gills  and  lungs,  supplies  the  oxygen,  wliicli  is  as 
necessary  for  life  as  food  itself ;  this  respiratory  system 
also  provides  for  the  passage  from  the  body  of  certain 
of  the  waste  gases,  like  carbonic  acid  gas  and  water 
vapor.  The  excretory  system  of  kidneys  and  similar 
structures  collects  the  ash-waste  produced  by  the  burn- 
ing tissues,  and  discharges  this  from  the  whole  mechan- 
ism, hke  the  ash  hoist  of  a  steamship.  The  circulatory 
system,  made  up  of  smaller  and  larger  vessels,  with  or 
without  a  heart,  transports  and  propels  the  blood 
through  the  body,  carrying  the  absorbed  foods,  the  sup- 


18  DOCTRINE   OF  EVOLUTION 

plies  of  oxygen,  and  the  waste  substances  of  various 
kinds.  All  of  these  four  systems  are  concerned  with 
*' commissary  "  problems,  so  to  speak,  which  every  in- 
dividual must  solve  for  and  by  itself. 

Another  group  of  systems  is  concerned  with  wider  rela- 
tions of  the  individual  and  its  activities.  For  example, 
the  motor  system  accomplishes  the  movements  of  the 
various  organs  within  the  body,  and  it  also  enables  the  or- 
ganism to  move  about ;  thus  it  provides  for  motion  and 
locomotion.  Systems  of  support,  comprising  bones  or 
shells,  occur  in  many  animals  where  the  other  organs  are 
soft  or  weak.  Perhaps  the  most  interesting  of  the  in- 
dividual systems  of  relation  is  the  nervous  system. 
The  strands  of  its  nerve  fibers  and  its  groups  of  cells 
keep  the  various  organs  of  the  body  properly  coor- 
dinated, whereas  in  the  second  place,  through  the 
sensitive  structures  at  the  surface  of  the  body,  they 
receive  the  impressions  from  the  outside  world  and  so 
enable  the  organism  to  relate  itself  properly  to  its  en- 
vironment. The  last  organic  system  differs  from  the 
other  seven  in  that  the  performance  of  its  task  is  of 
far  less  importance  to  the  individual  than  it  is  to  the 
race  as  a  whole.  It  is  the  reproductive  system,  with 
a  function  that  must  be  always  biologically  supreme. 
We  can  very  readily  see  why  this  must  be  so ;  it  is  be- 
cause nature  has  no  place  for  a  species  which  permits 
the  performance  of  any  individual  function  to  gain 
ascendency  over  the  necessary  task  of  perpetuating  the 
kind.     Nature  does  not  tolerate  race  suicide. 

All  organisms  must  perform  these  eight  functions 
in  one  way  or  another.  The  bacterium,  the  simplest 
animal,  the  lowest  plant,  the  higher  plants  and  animals, 


THE  LIVING   ORGANISM  19 

—  all  of  these  have  a  biological  problem  to  solve  which 
comprises  eight  terms  or  parts,  no  more  and  no  less. 
This  is  surely  an  astonishing  agreement  when  we  con- 
sider the  varied  forms  of  living  creatm-es.  And  perhaps 
when  we  see  that  this  is  true  we  may  understand  why 
adaptation  is  a  characteristic  of  all  organisms,  for  they 
all  have  similar  biological  problems  to  solve,  and  their 
lives  must  necessarily  be  adjusted  in  somewhat  sunilar 
ways  to  their  surroundings. 

Carrying  the  analysis  of  organic  structure  one  stop 
further,  it  is  found  that  the  various  organisms  are  them- 
selves complex,  being  composed  of  tissues.  A  frog's  log 
as  an  organ  of  locomotion  is  composed  of  the  protecting 
skin  on  the  outside,  the  muscles,  blood  vessels,  and  nerves 
below,  and  in  the  center  the  bony  supports  of  the  whole 
limb.  Like  the  organs,  these  tissues  are  differentiated 
structurally  and  functionally,  and  they  also  are  so 
placed  and  related  as  to  exhibit  the  kind  of  mechanical 
adjustment  which  we  call  adaptation.  The  tissues, 
then,  in  their  relations  to  the  organs  are  like  the  organs 
in  their  relations  to  the  whole  creature,  i.e.  adai)tod 
to  specific  situations  where  they  may  most  satisfactorily 
perform  their  tasks. 

Finally,  in  'the  last  analysis,  all  organisms  and  organs 
and  tissues  can  be  resolved  into  elements  which  are 
called  cells.  They  are  not  httle  hollow  cases,  it  is  true, 
although  for  historical  reasons  we  employ  a  word  that 
implies  such  a  condition.  They  are  unitary  masses  of 
living  matter  wdth  a  peculiar  central  body  or  nucleus, 
and  every  tissue  of  every  Hving  thing  is  composed  of 
them. 

The  cells  of  bone  differ  from  those  of  cartilage  mainly 


20  DOCTRINE  OF  EVOLUTION 

in  the  different  consistency  of  the  substances  secreted 
by  the  cells  to  lie  between  them;  skin  cells  are  soft- 
walled  masses  lying  close  together;  even  blood  is  a 
tissue,  although  it  is  fluid  and  its  cells  are  the  corpuscles 
which  float  freely  in  a  liquid  serum.  Thus  an  organism 
proves  to  be  a  complex  mechanism  composed  of  cells 
as  structural  units,  just  as  a  building  is  ultimately  a 
collection  of  bricks  and  girders  and  bolts,  related  to 
one  another  in  definite  ways. 

Our  analysis  reveals  the  living  creature  in  an  entirely 
new  light,  not  only  as  a  machinelike  structure  whose 
parts  are  marvelously  formed  and  coordinated  in 
material  respects,  but  also  as  one  whose  activities 
of  workings  are  ultimately  cellular  in  origin.  Struc- 
ture and  function  are  inseparable,  and  if  an  animal 
or  a  plant  is  an  aggregate  of  cells,  then  its  whole  varied 
life  must  be  the  sum  total  of  the  lives  of  its  constituent 
cells.  Should  these  units  be  subtracted  from  an  ani- 
mal, one  by  one,  there  would  be  no  material  organism 
left  when  the  last  cells  had  been  disassociated,  and  there 
would  be  no  organic  activity  remaining  when  the  last 
individual  cell-life  was  destroyed.  All  the  various 
things  we  do  in  the  performance  of  our  daily  tasks  are 
done  by  the  combined  action  of  our  muscle  and  nerve 
and  other  tissue  cells ;  our  fife  is  all  of  their  lives,  and 
nothing  more.  The  cell,  then,  is  the  physiological  or 
functional  unit,  as  truly  as  it  is  the  material  element  of 
the  organic  world.  Being  combined  with  countless 
others,  speciahzed  in  various  ways,  relations  are  estab- 
lished which  are  like  those  exhibited  by  the  human  be- 
ings constituting  a  nation.  In  this  case  the  life  of  the 
community  consists  of  the   activities   of   the   diverse 


THE  LIVING   ORGANISM  21 

human  units  that  make  it  up.  The  farmer,  the  manu- 
facturer, the  soldier,  clerk,  and  artisan  do  not  all  work 
in  the  same  way;  they  undertake  one  or  another  of 
the  economic  tasks  which  they  may  be  best  fitted  by 
circumstances  to  perform.  Their  differentiation  and 
division  of  labor  are  identical  with  the  diversity  in 
structure  and  in  function  as  well,  exhibited  by  the  cells 
of  a  living  creature.  We  might  speak  of  the  several 
states  as  so  many  organs  of  our  own  nation ;  the  com- 
mercial or  farming  or  manufacturing  communities  of 
a  state  would  be  like  the  tissues  forming  an  organ, 
made  up  ultimately  of  human  units,  which,  like  cells, 
are  engaged  in  similar  activities.  As  the  individual 
human  hves  and  the  activities  of  differentiated  eco- 
nomic groups  constitute  the  life  of  a  nation  and 
national  existence,  so  cell-Uves  make  the  living  of  an 
organism,  and  the  expressions  'division  of  labor"  and 
"differentiation"  come  to  have  a  biological  meaning 
and  application. 


The  cell,  then,  is  in  all  respects  the  very  unit  of  the 
organic  world.  Not  only  is  it  the  ultimate  structural 
element  of  all  the  more  familiar  animals  and  plants 
that  we  know,  as  the  foregoing  analysis  demonstrates, 
but,  in  the  second  place,  the  microscope  reveals  simple 
little  organisms,  like  Amoeba,  the  yeast  plant  and  })acteria, 
which  consist  throughout  their  lives  of  just  one  cell 
and  nothing  more.  Still  more  wonderful  is  the  fact  that 
the  larger  complex  organisms  actually  begin  existence 
as  single  cells.  In  three  ways,  therefore,  —  the  ana- 
lytic, the  comparative,  and  the  developmental,  —  the 


22  DOCTRINE  OF  EVOLUTION 

cell  proves  to  be  the  ''organic  individual  of  the  first 
order."  As  the  ultimate  biological  unit,  its  essential 
nature  must  possess  a  profound  interest,  for  in  its 
substance  resides  the  secret  of  hfe. 

This  wonderful  physical  basis  of  life  is  called  proto- 
plasm. It  contains  three  kinds  of  chemical  compounds 
known  as  the  proteins,  carbohydrates,  and  hydro- 
carbons. Proteins  are  invariably  present  in  living  cells, 
and  are  made  up  of  carbon,  hydrogen,  nitrogen,  sulphur, 
and  usually  a  Uttle  phosphorus.  The  elements  are 
also  combined  in  a  very  complex  chemical  way.  For 
example,  the  substance  called  haemoglobin  is  the  protein 
which  exists  in  the  red  blood  cells  and  which  causes  those 
cells  to  appear  light  red  or  yellow  when  seen  singly. 
Its  chemical  formula  states  the  precise  number  of  atoms 
which  enter  into  the  constitution  of  a  single  molecule 
as :  CgQQHggQNig^FeOj^g.  This  is  truly  a  marvelously 
complex  substance  when  compared  with  the  materials 
of  the  inorganic  world,  like  water,  for  example,  which  has 
the  formula  HgO.  And  just  as  the  peculiar  properties 
of  HgO  are  given  to  it  by  the  properties  of  the  hydrogen 
and  the  oxygen  which  combine  to  form  it,  just  so,  the 
scientist  believes,  the  marvelous  properties  of  protein 
are  due  to  the  assemblage  of  the  properties  of  the 
carbon  and  hydrogen  and  other  elements  which  enter 
into  its  composition. 

It  would  be  interesting  to  see  how  each  one  of  these 
elements  contributes  some  particular  characteristic 
to  the  whole  compound.  The  carbon  atom,  for  ex- 
ample, is  prone  to  combine  with  other  atoms  in  defi- 
nite varied  ways,  and  the  high  degree  of  complexity 
which  the  protein  molecule  possesses  may  depend  in 


THE  LIVING  ORGANISM  23 

greater  part  upon  the  combininp;  power  of  its  carbon 
elements.  The  nitrogen  atom  makes  the  protein  an 
extremely  volatile  compound,  so  that  the  latter  burns 
readily  in  the  tissue  cells ;  and  the  hydrogen  and  oxygen 
bring  their  specific  characteristics  to  the  total  molecule. 
And  furthermore,  it  is  evident  that  the  great  complexity 
of  this  constituent,  protein,  gives  to  protoplasm  its 
power  of  doing  work,  or,  in  a  word,  its  power  of  li\ing. 
In  constructing  it,  much  energy  has  been  absorbed  and 
stored  up  as  potential  energy,  and  so,  like  the  stored-up 
energy  in  a  watch  spring  or  in  gunpowder,  this  may  be 
converted,  under  proper  conditions,  into  the  kinetic 
energy  and  the  work  of  actual  operation.  On  account 
of  its  peculiar  and  complex  nature,  it  possesses  great 
capacity  for  burning  or  oxidization,  thus  serving  as  a 
source  of  vital  power.  It  burns  in  the  living  tissue  just 
as  coal  oxidizes  in  the  boiler  of  an  engine ;  its  atoms  fly 
apart  and  unite  with  oxygen  so  as  to  satisf}^  their  chem- 
ical affinities  for  this  substance.  If  we  could  only  see 
what  happens  to  the  protein  molecule  when  it  under- 
goes oxidization,  we  would  witness  a  violent  explosion, 
like  that  of  a  mass  of  gunpowder.  And  the  astonishing 
fact  is  that  this  process  is  actually  the  same  for  tlu^  li\in<i; 
molecule,  for  exploding  gunpowder,  and  for  the  fuel 
which  burns  in  the  locomotive  boiler.  Does  this  mean 
that  the  essential  process  of  what  we  call  life  is  a  cluMui- 
cal  one?  So  it  would  seem  on  the  basis  of  this  fact 
alone,  but  a  conclusion  must  be  deferred  until  we  reach 
a  later  point. 

The  second  kind  of  substance  which  we  find  in  pro- 
toplasm is  the  carbohydrate.  A  ty])ical  member  (^f 
this  group  is  common  sugar,  CgHjaOjj ;  another  sugar  has 


24  DOCTRINE  OF  EVOLUTION 

the  formula  C^.fl^fi^y  Starch  is  again  a  typical  carbo- 
hydrate, and  its  formula  is  CgHj^O^,  or  some  multiple  of 
this.  One  sees  at  a  glance  that  these  substances  agree 
in  having  twice  as  many  hydrogen  atoms  as  there  are 
oxygen  atoms,  the  same  proportion  that  the  hydrogen 
bears  to  the  oxygen  in  the  compound  water,  —  a 
characteristic  which  makes  it  easy  to  remember  the 
general  constitution  of  carbohydrate  as  compared 
with  the  protein.  The  substances  of  this  second  class 
are  obviously  much  less  complex,  both  as  regards  the 
different  kinds  of  atoms  and  in  respect  to  the  numbers 
of  each  kind  that  enter  into  the  formation  of  a  single 
molecule.  Therefore  the  carbohydrates  do  not  possess 
so  much  power  or  energy  as  the  protein  molecule ; 
in  short,  they  are  not  such  good  fuels  for  the  living 
mechanism. 

Finally,  we  find  almost  always  in  protoplasm  other 
substances  composed  of  carbon  and  hydrogen  and  oxygen 
which  are  called  hydrocarbons,  distinguished  from  carbo- 
hydrates by  the  fact  that  the  number  of  oxygen  atoms  is 
less  than  half  the  number  of  hydrogen  atoms.  These 
substances  are  the  fats  and  oils  of  various  kinds,  less 
powerful  sources  of  energy  than  the  proteins,  but  they 
contain  more  potential  energy  than  the  carbohydrates 
because  they  are  more  oxidizable. 

Besides  the  characteristic  substances  of  these  three 
classes,  protoplasm  contains  certain  other  chemical 
compounds,  like  the  various  salts  of  sodium,  chlorine, 
magnesium  and  potassium,  and  a  few  others,  which 
bring  the  list  of  chemical  elements  to  the  number  twelve. 
We  have  already  noted  how  strikingly  small  and 
restricted   is   the   list   of   elements    composing   living 

PROPERTY  LIBRARY 

At  C.  State  Cc '    7e 


THE  LIVING  ORGANISM  25 

matter  as  compared  with  the  long  array  of  eighty-odd 
different  kinds  of  chemical  atoms  existing  in  the  world 
as  a  whole. 

But  an  astonishing  result  is  reached  through  the  brief 
analysis  we  have  just  made.  It  is  this :  we  do  not 
find  peculiar  kinds  of  atoms  which  occur  exclusively 
in  living  matter ;  the  materials  are  exactly  the  same 
as  those  of  the  outer  world.  In  short,  the  elements 
of  both  the  organic  and  inorganic  divisions  of  the 
universe  prove  to  be  the  same.  Carbon  is  carbon, 
whether  it  is  part  of  the  substance  of  a  living  brain  cell, 
or  black  inert  coal,  or  the  glistening  diamond,  or  an 
incandescent  part  of  the  fiery  sun.  Hydrogen  is  the 
same,  whether  it  be  a  constituent  of  the  ocean,  of  the  air, 
or  of  the  hving  muscle  fiber.  And  so  it  is  with  all  of 
the  other  elements  of  the  living  mechanism.  This  starts 
us  upon  a  line  of  thought  which  leads  to  a  significant 
conclusion,  namely,  that  a  living  thing  which  seems  so 
distinct  and  permanent  is  after  all  only  a  temporary  ag- 
gregate of  elements  which  come  to  it  from  the  not-hving 
world;  existing  for  a  time  in  peculiar  combinations 
which  render  life  possible,  they  pass  incessantly  away 
from  the  living  thing  and  return  to  the  inorganic  world. 
.Every  breath  we  draw  sends  out  particles  which  were 
at  one  time  living  portions  of  ourselves;  every  move- 
ment we  make  involves  the  destruction  of  living  muscle 
cells,  whose  protoplasm  breaks  down  into  the  ash  and 
^as  and  fluid  wastes  which  eventually  return  to  the 
v/orld  of  dead  things.  A  tree  loses  its  Hving  leaves  with 
each  recurring  season,  and  the  antlers  of  the  stag  are 
lost  amiually,  to  be  replaced  anew.  Indeed  the  major 
part  of  some  organisms  is  itself  actually  dead.     The 


26  DOCTRINE  OF  EVOLUTION 

bones  and  hair  and  nails  of  such  an  animal  as  a  cat  are 
almost  entirely  hfeless,  even  though  they  are  integral 
and  necessary  portions  of  the  organism  as  a  whole. 
They  are  constructed  by  living  protoplasm  which  has 
died  in  their  making.  Thus  without  going  beyond  the 
boundaries  of  the  individual  body,  these  substances  have 
passed  from  the  sphere  of  life,  and  are  dead.  The  ap- 
parent gap  on  the  other  side  between  the  hfeless  and 
living  world  is  equally  imaginary,  for  our  living  sub- 
stance is  continually  replenished  and  rebuilt  from  the 
elements  of  our  dead  foods.  So,  as  Huxley  says,  a 
Hving  organism  is  like  a  flame  or  a  whirlpool,  which  is 
an  ever  changing  though  seemingly  constant  individual- 
ity. We  look  at  a  gas  flame,  and  we  see  in  the  flame 
itself  those  particles  of  gas  which  have  come  through 
the  pipe  to  be  agitated  violently  in  the  higher  temper- 
ature of  the  flame  as  they  are  oxidized  or  burnt.  These 
particles  immediately  pass  off  as  carbonic  acid  gas  and 
water  vapor  which  are  no  longer  parts  of  the  flame. 
A  fountain  is  continually  replenished  by  the  water 
which  is  not-fountain,  but  which  becomes  for  the  time 
a  part  of  the  graceful  jet,  falling  out  and  away  as  it 
leaves  the  fountain  itself.  Just  so  a  living  organism 
is  an  ever  changing,  ever  renewed,  and  ever  destroyed 
mass  of  little  particles  —  the  atoms  of  the  inorganic 
world  which  combine  and  come  to  life  for  a  time,  but 
which  return  inevitably  to  the  world  of  lifeless  things. 
This  is  one  of  the  most  fundamental  facts  of  biology. 
The  independence  of  a  living  thing  like  a  human  being 
or  a  crustacean  is  a  product  of  the  imagination.  How 
can  we  be  independent  of  the  environment  when  we 
are  interlocked  in  so  many  ways  with  inorganic  nature  ? 


THE   LIVING   ORGANlSiM  o 


^i 


Our  very  substance  with  its  energies  has  been  wrested 
from  the  environment;  and  as  we,  Hke  all  other  living 
things,  must  replenish  our  tissues  as  we  wear  out  in  the 
very  act  of  living,  we  cannot  cease  to  maintain  the 
closest  possible  relations  with  the  environment  with- 
out surrendering  our  existence  in  the  battle  of  life. 

From  the  foregoing  discussion,  it  will  be  evident,  I 
am  sure,  that  there  is  ample  justification  for  the  biolo^rj. 
cal  dictum  that  a  Hving  individual  is  a  mechanism. 
Not  only  is  the  organism  composed  always  of  cell 
units  grouped  mechanically  in  tissues  and  organs  and 
organic  systems;  not  only  are  the  operations  which 
make  up  its  life  constant  and  regular  under  similar 
conditions  ;  not  only  is  the  whole  creature  mechanically 
connected  with  the  inorganic  world;  but  above  all  the 
whole  activity  of  a  biological  individual  is  concerned 
necessarily  and  again  mechanically  with  the  acciuisition 
of  materials  endowed  with  energy,  which  materials  and 
energy  are  mechanically  transformed  into  living  matter 
and  its  life.  Even  though  an  organism  is  so  much 
more  complex  than  a  locomotive,  and  so  plastic,  never- 
theless, in  so  far  as  both  are  mechanisms, the  conception 
of  the  evolution  of  the  former  ma}^  be  much  more  readily 
understood  through  a  knowledge  of  the  historical  trans- 
formation of  the  latter. 


What,  now,  is  life?  To  most  people  ''life  seems  to 
be  something  which  enters  into  a  combination  of  carbon 
and  hydrogen  and  the  other  elements,  and  makes  this 
complex  substance,  the  protoplasm,  perform  its  va- 
rious activities."     Nearly  eveiy  one  finds  it   difTicult 


28  DOCTRINE  OF  EVOLUTION 

to  regard  life  and  vitality  as  anything  but  actuating 
principles  that  exist  apart  from  the  materials  into 
which  they  enter,  and  which  they  seem  to  make  alive. 
According  to  this  general  conception,  ''life  is  something 
like  an  engineer  who  climbs  into  the  cab  of  the  locomo- 
tive and  pulls  the  levers  which  make  it  go,"  as  health 
might  supposedly  be  regarded  as  something  that  does 
not  inhere  in  well-being,  but  gets  into  the  body  to  alter 
it.  But  is  this  conception  really  justified  by  the  facts 
of  animal  structure  and  physiology?  Let  us  recall 
the  steps  of  our  analysis.  The  living  organism  is  a 
collection  of  differentiated  parts,  the  organs;  the 
life  of  an  organism  is  a  series  of  activities  of  the  several 
organic  systems  and  organs.  If  we  could  take  away 
one  organ  after  another,  there  would  be  nothing  left 
after  the  last  part  had  been  subtracted.  In  a  similar 
manner,  the  activities  of  organs  prove  to  be  the  com- 
bined activities  of  the  tissue-cells,  and  again  the  truth 
of  this  statement  will  be  clear  when  we  imagine  the 
result  of  taking  away  one  cell  after  another  from 
organisms  like  the  frog  or  tree.  When  the  last  cell 
had  been  withdrawn,  there  would  be  nothing  left  of 
the  frog's  structure,  and  there  would  be  no  element 
of  the  frog's  life.  It  is  true  that  the  particular  way  the 
tissue-cells  are  combined  is  of  primary  importance,  but 
it  is  none  the  less  true  that  the  life  of  a  cell  is  the  kind 
of  element  out  of  which  the  life  of  even  the  most  com- 
plex organism  is  built.  And  we  have  seen  that  the 
essential  substance  of  a  cell  is  a  complex  chemical 
compound  we  call  protoplasm,  whose  elements  are 
identical  with  chemical  substances  outside  the  living 
world.     Is  there  any  ground  for  supposing  that  the 


THE  LIVING  ORGANISM  29 

properties  of  protoplasm  are  due  to  any  other  raiises 
than  those  which  may  be  found  in  the  chemical  and 
physical  constitution  of  protophism?  In  brief,  is  life 
physics  and  chemistry?  Nowadays  the  majority  of 
biologists  believe  that  it  is.  Just  as  the  properties 
of  water  are  contributed  by  the  elements  hydrogen  and 
oxygen  which  unite  to  form  it,  just  so  the  marvelous 
properties  of  protoplasm  are  regarded  as  the  inevitable 
derivatives  of  the  combined  properties  of  the  various 
chemical  elements  which  constitute  protoplasm.  Biolo- 
gists have  known  for  more  than  a  century,  since  the 
work  of  Lavoisier  and  Laplace  in  1780,  that  the  funda- 
mental process  of  the  living  mechanism  is  oxidation, 
and  that  this  process  is  the  same,  as  they  said,  for  the 
burning  candle  and  the  guinea  pig.  Beginning  with 
Woehler,  in  1828,  scores  of  students  of  physiological 
chemistry  have  duplicated  the  chemical  processes  of 
living  matter,  which  were  regarded  as  so  peculiar  to  the 
living  organism  that  they  seemed  to  be  due  to  the  oper- 
ation of  a  non-mechanical  and  vital  cause.  Tlio  in\'es- 
tigator  mentioned  was  the  first  to  construct  artificially 
from  inorganic  substances  the  nitrogen-containing 
ash  product  of  the  living  organism  called  urea.  Now 
hundreds  of  so-called  organic  com]K)unds  have  been 
made  synthetically  and  their  number  is  added  to  week 
after  week.  Therefore,  the  biologist  who  finds  that  a 
physical  and  chemical  analysis  of  some  vital  processes 
is  possible,  and  that  the  analysis  is  being  extended 
with  astonishing  rapidity,  finds  himself  unal)le  to 
regard  protoplasmic  activity  as  anything  dilTerent  in 
kind  or  category  from  the  processes  of  physics  and 
chemistry  which  go  on  in  the  world  of  dead  things. 


30  DOCTRINE  OF  EVOLUTION 

It  is  true  that  even  at  the  present  time  some  biologists 
are  reluctant  to  accept  the  thoroughgoing  mechanical 
interpretation  of  organic  phenomena,  partly  because 
these  are  so  complex  that  their  ultimate  constituents 
cannot  be  discerned,  but  more  often  on  account  of  the 
apparently  purposeful  nature  of  biological  processes. 
Some,  indeed,  have  gone  so  far  as  to  postulate  some- 
thing like  consciousness  which  controls  and  directs  the 
formation  of  protoplasm,  and  the  exercise  of  its  dis- 
tinctive properties  in  the  way  of  growth,  reproduction, 
and  embryonic  development  into  the  adapted  adult. 
But  the  fact  remains  that  wherever  analysis  has  been 
possible  the  constituent  elements  of  an  organic  process 
prove  to  be  physical  and  chemical.  Protoplasm  differs 
from  inorganic  materials  only  in  its  complexity  and 
in  the  properties  which  seem  to  owe  their  existence 
to  this  complexity.  As  Huxley  points  out,  it  is  no  more 
justifiable  to  postulate  the  existence  of  a  vitalistic 
principle  in  protoplasm  than  it  would  be  to  set  up  an 
aquosity"  to  account  for  the  properties  of  water,  or  a 
saltness"  for  the  qualities  of  a  certain  combina- 
tion of  sodium  and  chlorine.  We  may  not  know  how 
the  elements  produce  the  properties  of  the  compound, 
but  we  do  know  that  such  properties  are  the  invariable 
products  of  their  respective  constituents  in  combina- 
tion. As  far  as  the  evidence  goes,  it  tells  strongly  and 
invariably  in  favor  of  the  mechanistic  interpretation. 

Under  the  present  limitations,  it  is  impossible  to  give 
this  subject  the  further  discussion  it  deserves.  It  is 
not  our  purpose  to  review  the  origin  of  life  in  times 
past,  and  the  origin  of  living  matter  from  inorganic 
constituents,  though  the  subject  is  one  of  the  most 


THE  LIVING   ORGANISM  31 

important  in  the  field  of  cosmic  evolution.  We  must 
begin  with  the  hving  organism ;  and  how  the  first  one 
arose  must  be  of  less  importance  to  us  than  tlie  knowl- 
edge of  its  mechanical  constitution  and  of  its  mechani- 
cal operation.  Of  far  greater  value  is  the  realizalicjn 
that  a  living  creature  is  not  an  independent  thing,  but 
that,  on  the  contrary,  it  must  hold  the  closest  possible 
relations  with  the  world  of  materials  and  energies  con- 
stituting its  environment.  We  must  again  insist  upon 
the  importance  of  that  mechanical  adjustment  to  the 
conditions  of  life  which  is  the  universal  characteristic 
of  plants  and  animals.  It  is  the  history  of  these  crea- 
tures and  the  origin  of  their  adapted  conditions  that 
we  are  called  upon  to  study.  We  must  scrutinize  the 
nature  of  to-day  to  see  if  we  can  find  evidence  that 
evolution  is  true,  and  if  we  can  discern  the  forces  which, 
acting  upon  the  living  mechanism  as  man  has  dealt 
with  machines,  might  bring  the  various  species  of  the 
present  day  to  their  modern  forms. 


We  have  now  learned  that  evolution  means  a  common 
ancestry  of  living  forms  that  have  come  to  differ  in  the 
course  of  time ;  our  common  reason  has  shown  us  also 
that  organisms  are  in  a  true  sense  complicated  cluMnical 
mechanisms  adapted  to  meet  the  conditions  under  which 
they  must  operate.  We  come  now  to  the  evidences 
offered  by  the  organic  world  that  evolution  is  true  and 
that  natural  forces  control  its  workings.  Clearly  the 
examination  of  the  matter  oi  fact  is  independent  of  the 
question  of  method.  For  just  as  the  chemist  may  ex- 
periment with  various  substances  to  see  if  they  will 


32  DOCTRINE  OF  EVOLUTION 

dissolve  in  water  and  not  in  alcohol  before  it  is  neces- 
sary or  desirable  for  him  to  take  up  the  further  studies 
of  the  laws  of  solution,  so  reasonable  grounds  must  be 
found  for  regarding  evolution  as  true  before  passing  to 
its  method  of  accomplishment.  And  in  the  following 
discussions,  the  animals  will  be  used  almost  exclusively, 
not  because  the  study  of  plants  fails  to  discover  the 
same  relations  and  principles,  but  because  the  better 
known  animal  series  is  more  varied  and  extensive, 
and  above  all  for  the  reason  that  the  human  organism 
arrays  itself  as  the  highest  term  of  the  animal  series. 

In  the  complete  scheme  adopted  by  most  naturalists, 
five  categories  include  the  evidences  bearing  upon  the 
fact  of  evolution.  These  are  Classification;  Comparative 
Anatomy,  or  Morphology ;  Comparative  Development, 
or  Embryology ;  Palceontology,  which  comprises  the  facts 
provided  by  fossil  relics  of  animals  and  plants  of  earlier 
geological  ages ;  and  Geographical  Distribution.  Each  of 
these  divisions  includes  a  descriptive  and  analytical 
series  of  facts,  whose  characteristics  are  ^^ explained"  or 
summarized  in  the  form  of  the  general  principles  of 
the  respective  divisions.  Such  principles,  taken  singly 
and  collectively,  constitute  the  evidences  of  evolution. 

The  particular  nature  of  any  one  of  these  categories, 
evolved  in  the  development  of  science  practically  in  the 
order  stated,  depends  upon  the  special  quality  of  an 
animal  which  it  selects  for  comparison  and  organization 
in  connection  with  other  similar  facts,  and  also  in  its 
own  mode  of  viewing  its  facts.  One  and  the  same  or- 
ganism may  present  materials  for  two,  three,  or  even 
all  five  of  these  divisions,  for  they  are  by  no  means 
mutually  exclusive.     For  example,  a  common  cat  pos- 


THE   LIVING   ORGANISM  33 

sesses  certain  definite  characteristics  which  pive  it  a 
particular  place  when  animals  more  or  less  like  it  are 
grouped  or  classified  according  to  their  degrees  of  re- 
semblance and  difference,  in  small  genera  of  very  similar 
forms,  in  larger  tribes  or  orders  of  similar  genera,  and  in 
more  and  more  inclusive  groups  of  these  lesser  divisions, 
such  as  the  classes  and  phyla,  or  main  branches  of  the 
animal  tree.  The  common  cat  and  its  relatives  are 
even  earlier  to  be  regarded  as  anatomical  subjects,  and 
their  thorough  analysis  belongs  to  comparative  anat- 
omy, —  a  name  which  explains  itself.  The  purpose 
of  this  department  of  natural  history  is  to  explore  the 
entire  range  of  animal  forms  and  animal  structures,  and 
to  determine  the  degree  of  resemblance  and  difference 
exhibited  by  the  general  characters  of  entire  organisms 
and  by  the  special  qualities  of  their  several  systems 
of  organs.  It  provides  the  data  from  which  classifica- 
tion selects  those  w^hich  indicate  mutual  afliiiities  with 
greatest  precision  and  surety.  But  its  materials  are 
all  the  facts  of  animal  structure,  and  because  each  and 
every  known  organism  can  be  and  must  be  studied, 
the  investigator  engaged  in  formulating  the  evidence 
of  evolution  has  at  his  disposal  all  the  data  referring  to 
the  entire  realm  of  animals.  The  data  of  embryology 
are  likewise  coextensive  with  the  territory  of  the  animal 
world,  for  w^e  do  not  know  of  any  form  which  docs  not 
change  in  the  course  of  its  life  history.  An  adult  cat 
is  the  product  of  a  kitten  which  is  itself  the  resuh  of  a 
long  series  of  changes  from  earlier  and  simpler  conditions. 
In  so  far  as  it  deals  with  structures  in  the  making,  em- 
bryology is  a  study  of  anatomy,  but  as  it  is  concerned 
primarily  with  all  of  the  plastic  remodeling  which  an- 


34  DOCTRINE  OF  EVOLUTION 

imals  undergo  during  the  production  of  their  final  forms, 
it  is  an  independent  study.  Nevertheless  we  shall  learn 
how  intimate  are  the  relations  of  these  two  divisions  of 
zoology  and  how  the  evolutionary  teachings  of  each  body 
of  fact  support  and  supplement  those  of  the  other. 

Palaeontology  searches  everywhere  among  the  de- 
posits of  earlier  ages  for  links  to  be  fitted  into  their 
proper  sequence  of  time,  from  which  it  constructs  the 
chain  of  diverse  types  leading  down  to  the  species  of 
the  present.  A  cat  of  to-day  is  therefore  viewed  in 
an  entirely  different  connection,  as  the  last  term  in  a 
consecutive  series  of  species.  Forming  alliances  with 
geology,  and  even  with  physics  and  chemistry,  this 
department  of  zoology  endeavors  to  reconstruct  the 
past  from  what  it  learns  to-day  about  organisms  and 
the  conditions  under  which  they  live.  Finally  the 
observations  that  cats  of  various  kinds  do  not  occur 
everjrwhere  in  the  world,  but  only  in  certain  more  or 
less  restricted  localities,  belong  to  the  subject  of  geo- 
graphical distribution,  and  illustrate  its  nature. 

Our  task  is  to  learn  the  teachings  of  these  several 
divisions  by  recalling  and  putting  together  what  we 
know  already  about  the  commonest  animals,  or  noting 
what  can  be  observed  in  a  visit  to  a  zoological  garden 
and  aquarium.  On  account  of  the  present  limitations 
of  time,  the  subject  of  classification  will  be  combined 
with  comparative  anatomy ;  embryology  will  be  taken 
up  together  with  these  subjects ;  palaeontology  will  be 
the  main  subject  of  the  next  discussion,  which  will  in- 
clude also  a  brief  statement  of  the  meaning  of  dis- 
tribution. Then  we  will  be  prepared  to  study  nature 
to  see  how  evolution  works. 


II 


THE     STRUCTURE     AND     DEVELOPMENT    OF    ANIMALS    AS 

EVIDENCE    OF   EVOLUTION 

In  order  to  become  acquainted  with  the  way  the 
structures  of  animals  provide  evidences  of  evolution,  it 
is  by  no  means  necessary  to  review  the  entire  range  of 
their  forms,  because  research  has  discovered  that  the 
principles  of  relationship  are  universal  among  animals, 
and  that  any  group  of  examples  will  demonstrate  what 
is  taught  by  comparative  anatomy  as  a  whole.  The 
commonest  creatures  may  serve  us  best  in  order  that 
we  may  come  to  view  evolution  as  a  process  that  in- 
volves each  and  every  living  thing  that  we  know,  and 
not  as  something  w^hich  belongs  only  to  the  remote  and 
unknown  past. 

Let  us  begin  with  the  common  cat  and  the  group  of 
carnivora  or  flesh-eating  animals  to  which  it  belongs. 
As  we  pass  along  the  streets  of  the  city,  we  will  see  many 
cats  which  differ  in  some  details,  though  they  resenil)le 
one  another  closely.  WTiile  they  vary  somewhat  in 
form,  the  range  in  this  quality  is  not  so  noticeable  a.^  in 
the  matter  of  color;  some  of  them  will  be  gray,  some 
maltese,  while  others  w^ill  be  yellowish  or  black,  and 
they  w^ll  differ  in  the  striped  or  spotted  character  of 
their  coloration.  We  readily  classify  them  all  as  "cats" 
in  spite  of  their  differences,  because  they  arc  alike  in 

35 


36  DOCTRINE  OF  EVOLUTION 

so  many  ways  that  we  have  learned  to  associate  as  the 
distinguishing  characteristics  of  these  animals,  and  to 
label  —  ''cat."  The  animals  which  we  might  see  in  a 
walk  of  several  blocks  may  reasonably  be  regarded  as 
offspring  of  the  same  pair  of  ancestors  of  a  few  years 
back,  even  though  they  are  dissimilar.  We  all  know  that 
the  kittens  of  one  and  the  same  litter  vary :  no  two  of 
them  are  ever  exactly  alike  in  color  or  disposition  or 
voice  or  size,  nor  is  any  one  identical  with  either  of  its 
parents,  although  it  may  be  necessary  to  employ  exact 
means  of  measuring  them  in  order  to  demonstrate  their 
variation.  The  fact  of  difference,  then,  is  surely  not 
inconsistent  with  even  the  closest  ties  of  blood,  and  we 
do  not  need  to  go  beyond  the  scope  of  daily  observation 
to  find  that  this  is  true  in  nature  wherever  we  look. 

Should  we  extend  our  observations  so  as  to  include 
the  cats  of  Boston  and  Philadelphia  and  San  Francisco, 
the  animals  would  probably  vary  over  a  wider  range, 
but  they  would  be  so  similar  to  New  York  cats  in  their 
make-up  that  we  would  have  no  difficulty  in  regarding 
them  and  all  the  others  of  the  United  States  as  the 
descendants  of  a  single  pair  of  ancestors,  perhaps 
brought  over  in  the  ^'Mayflower."  But  why  does  this 
view  seem  justified?  Because  experience  has  taught 
us  that  the  living  things  which  resemble  each  other 
most  closely  are  those  which  are  most  intimately  bound 
by  ties  of  blood  and  common  heritage.  It  is  ''natural" 
for  relatives  to  resemble  one  another  more  than  per- 
sons not  related,  and  for  brothers  and  sisters  to  be  more 
ahke  than  cousins.  Science  does  not  refer  to  something 
outside  everyday  observation  when  it  states  that  the 
possession  by  two  animals  of  a  great  body  of  similar 


STRUCTURE  AND   DEVELOPMENT  37 

characters  beneath  their  minor  differences  is  an  indication 
of  their  common  ancestry. 

Thus  at  the  very  outset  our  simple  ilUistration  es- 
tabhshes  the  most  fundamental  principle  of  comparative 
anatomy.  Let  us  see  how  it  works  further.  The 
Manx  cat  possesses  an  abbreviated  tail,  although  in 
other  respects  it  is  practically  the  same  as  the  familiar 
long-tailed  form ;  the  Angora  and  the  Persian  dilTer 
in  having  long  hair.  All  of  these  animals  are  so  much 
alike  in  so  many  respects,  and  so  closely  resemble 
the  wild  cats,  that  it  is  not  unreasonable  to  regard  them 
all  as  the  descendants  of  the  same  original  wild  ances- 
tors, and  as  the  varying  products  of  lines  which  branched 
out  from  the  same  stock  in  different  directions  and 
at  different  times.  It  is,  in  a  word,  their  ''cat-n€ss" 
which  demonstrates  their  relationships.  But  connnon 
sense  need  not  stop  here.  Guided  by  the  facts  of  ana- 
tomical similarity,  it  convinces  us  that  the  dun-colored 
lion  and  puma,  the  striped  tiger  and  the  spotted  lcoi)ard 
are  simply  cats  of  a  larger  growth  whose  remoter 
ancestry  is  one  with  that  of  the  previously  cited  forms. 
Not  until  we  explore  and  compare  their  several  systems 
do  we  see  how  thoroughgoing  is  their  uniformity  in 
structural  plan.  And  because  reason  justifies  the  view 
regarding  the  origin  of  domestic  cats  from  wild  ances- 
tors, the  evolution  of  all  the  various  members  of  the  cat 
tribe  must  be  acknowledged.  These  animals  exhiiiit 
a  fundamental  likeness,  which,  to  employ  a  musical 
analogy,  is  the  ''theme"  of  "cai-ncss/'  and  they  are  so 
many  variations  of  this  theme. 

The  members  of  another  tribe  of  the  familiar  car- 
nivora  display  in  their  own  way  the  same  kinii  of  evi- 


38  DOCTRINE  OF  EVOLUTION 

dences  of  relationship.  The  varieties  of  domesticated 
dogs  differ  far  more  widely  among  themselves  than  do 
common  cats,  yet  their  community  of  ancestry  is 
demonstrated  not  only  by  structural  resemblances,  but 
also  by  the  striking  fact  that  forms  as  diverse  as  the 
greyhound  and  the  fox  terrier  can  be  crossed.  Here 
again  there  are  wild  forms,  like  the  wolf  and  fox  and 
jackal,  so  like  the  domesticated  members  of  the  dog 
tribe  that  we  cannot  fail  to  recognize  a  common  '^dog- 
ness^'  and  its  significance  as  evidence  of  the  relationship 
in  ancestry  of  all  these  animals. 

Extending  our  survey  so  as  to  include  the  other 
tribes  of  flesh-eaters,  identical  principles  come  to  light. 
One  is  compelled  to  regard  the  polar  and  grizzly  bears 
as  obvious  blood  relatives  of  the  brown  bear,  and  even 
of  the  raccoon  of  our  own  territory.  Instead  of  walking 
upon  their  toes  like  cats  and  dogs,  these  animals  plant 
their  feet  fiat  upon  the  ground ;  and  they  agree  in  many 
other  details  of  structure  that  place  them  together,  but 
somewhat  apart  from  the  other  tribes.  The  many 
kinds  of  seals  and  walruses  and  sea  elephants  form 
still  another  group  displaying  similar  bodily  characters, 
but  differing  more  widely  from  the  '^cat  theme"  in 
these  differences.  They  are  all  true  carnivora,  but  in 
the  course  of  their  evolution  they  have  progressively 
changed  so  as  to  be  adapted  to  life  in  the  water  where 
they  find  their  prey.  The  bones  of  the  limbs  are  the 
same  in  number  and  arrangement  as  in  the  cat's  limb, 
but  the  seal's  anterior  appendage  or  ^'arm"  has  altered 
in  numerous  ways  so  as  to  become  an  efficient  flexible 
paddle,  while  the  hind  limbs  have  shifted  posteriorly, 
very  much  as  screw  propellers  have  evolved  in  the  his- 


STRUCTURE  AND   DEVELOPMi:XT  :-{0 

tory  of  steam  vessels.  How  the  mein])ors  of  the  seal 
tribe  have  changed  in  their  descent  from  purely-  terres- 
trial ancestors  is  partly  explained  by  such  intermediate 
animals  as  the  otter.  This  form  is  adapted  by  its 
slender  body  and  partly  webbed  feet  to  a  semi-a(iuatic 
hfe ;  it  seems  to  have  halted  at  a  point  beyond  which  all 
of  the  seals  have  passed  in  their  evolution. 

Each  one  of  these  tribes  by  itself  provides  conclusive 
evidence  of  evolution,  for  it  is  most  reasonable  to  regard 
the  ''theme"  in  every  case  as  a  product  of  common 
inheritance,  while  the  variations  of  any  theme  are  best 
understood  as  the  results  of  adaptive  changes  in  various 
directions.  But  the  examples  have  disclosed  a  larger 
relation  and  a  principle  of  wider  scope,  as  indeed  the 
assignment  of  all  these  tribes  to  the  single  natural 
group  of  the  carnivora  implies.  These  tribes  are  put 
together  because  comparative  anatomy  finds  that  the 
common  characters  of  all  cats  are  fundamentally  like 
those  of  all  dogs  and  bears  and  seals,  and  in  these  com- 
mon qualities  the  carnivora  differ  from  all  other  mam- 
malia. Does  this  mean  that  the  branches  which  bear 
respectively  the  various  members  of  the  several  tribes 
are  outgrowths  of  a  single  limb  of  the  evolving  animal 
tree?  Science  does  not  hesitate  to  give  an  affirmative 
answer,  because,  as  in  the  case  of  the  similar  but  vary- 
ing domestic  cats,  no  other  explanation  of  trii)al  re- 
semblance in  structure  seems  so  reasonable  and  natural. 

So  far  the  examples  have  been  taken  from  one  order 
of  the  highest  class  of  backboned  animals,  called  mam- 
malia. When  our  survey  is  extended  to  other  divisions 
of  this  class,  additional  laws  of  organic  relationship  are 
discovered.     If  in  a  series  of  evolving  generations  the 


40  DOCTRINE  OF  EVOLUTION 

line  of  modification  proceeding  from  a  terrestrial  animal 
like  a  cat  to  semi-aquatic  and  marine  types  substan- 
tially like  an  otter  and  a  seal  should  be  carried  further, 
it  will  inevitably  lead  to  forms  possessing  characters 
such  as  those  displayed  by  whales  and  the  related  por- 
poises, dolphins,  and  narwhals  of  the  order  cetacea.  In 
their  make-up  all  of  these  animals  clearly  possess  the 
general  characteristics  of  mammals,  and  they  constitute 
collectively  another  limb  which  has  sprung  from  the 
same  stock  as  the  carnivora,  although  at  an  earlier 
time.  This  we  believe  because  of  their  plan  of  body 
and  because  their  peculiar  organization  fits  them  even 
more  perfectly  than  the  seals  for  aquatic  existence  that 
is  their  only  possible  mode  of  life.  In  the  case  of  the 
whales  the  bony  framework  of  the  fore  limb  is  again 
like  that  of  the  cat's  leg,  although  the  whole  structure  is 
a  flexible  finlike  paddle.  The  hind  limb  has  disap- 
peared as  an  efficient  organ,  but  the  significant  fact 
is  that  small  rudiments  of  hind  limbs  are  present  just 
where  corresponding  structures  are  placed  in  the  seal. 
These  vestiges  cannot  be  reasonably  accounted  for, 
unless  they  are  the  degenerate  hinder  limbs  of  a  remote 
four-footed  ancestor.  Furthermore  the  unborn  whale 
possesses  a  complete  coat  of  hair,  which  is  afterwards 
replaced  by  blubber;  but  hair  is  a  thatchlike  coat  to 
shed  rain,  as  the  way  the  hairs  lie  on  a  terrestrial  mam- 
mal indicates.  We  are  therefore  forced  to  conclude 
that  whales  have  originated  from  four-footed  animals 
walking  about  on  land,  because  no  opposed  explana- 
tion gives  so  reasonable  an  interpretation  of  the 
observed  facts. 

Another  group  of  famiUar  animals  materially  rein- 


STRUCTURE   AND  DEVELOPMENT  41 

forces  the  results  already  estal)lished.  After  what  has 
been  said,  it  will  not  be  diflicult  to  perceive  the  meaning 
of  the  resemblances  among  mice  of  the  house*  and  ticld, 
and  of  rats  and  rabbits  and  squirrels.  All  of  them 
possess  heavy  curved  gnawing  teeth,  or  incisors,  and 
lack  the  flesh-tearing  or  canine  teeth.  They  agree 
in  many  other  respects  which  distinguish  them  as  a 
separate  natural  order  of  the  mammals  called  the 
rodentia.  Again  we  find  a  highly  aberrant  form  in  the 
flying  squirrel,  which  leads  toward  an  order  with  another 
plan  of  body.  This  animal  is  a  true  rodent,  which 
lengthens  its  leap  from  branch  to  branch  by  means  of  a 
fold  of  skin  stretching  between  its  fore  and  its  hind 
limbs.  It  is  an  animated  aeroplane,  and  it  shows  in 
part  how  bats  have  originated.  The  wing  of  a  bat  is  an 
elastic  membrane  stretching  not  only  between  the  two 
legs  of  one  side,  but  also  between  the  greatly  lengthened 
^^ fingers"  of  the  fore  limb.  But  the  bones  of  arm,  wrist, 
and  fingers  are  almost  precisely  the  same  in  number 
and  relation  as  in  walking  forms.  The  fact  that  this 
peculiar  wing  adheres  to  a  plan  belonging  to  the  anterior 
legs  of  walking  or  climbing  types  has  no  reasonable 
explanation  save  that  of  evolution. 

The  well-known  group  of  hoofed  animals,  including 
horses  and  cattle,  is  also  valuable  for  our  present  pur- 
poses, as  well  as  in  a  later  connection  when  the  evidence 
of  fossils  is  described.  The  elephant  possesses  five  toes 
armed  with  well-developed  nails  or  hoofs.  A  tapir  has 
four  or  three  toes,  and  it  would  seem  that  its  ancestor 
had  had  five  toes,  of  which  one  or  two  had  been  lost. 
A  rhinoceros  possesses  three  toes,  and  its  foot  is  con- 
structed internally  like  the  elephant's  with  the  outer 


42  DOCTRINE  OF  EVOLUTION 

elements  absent.  The  horse  comes  last  with  one  large 
toe  and  hoof,  but  on  either  side  of  the  main  bones  of 
this  digit  are  vestiges  of  what  must  have  been  toes  in 
its  ancestors.  Among  the  even-toed  forms  the  hippopot- 
amus has  four  which  reach  the  ground,  with  a  vestige 
of  a  fifth,  so  this  animal  has  apparently  descended  from 
a  typical  mammal  with  the  full  number  along  a  different 
line  from  that  taken  by  the  odd-toed  forms.  A  pig 
has  a  cloven  hoof,  made  up  of  what  we  may  call  the 
third  and  fourth  members  of  a  series  of  five  digits,  but 
the  second  and  fifth  fingers  and  toes  are  present, 
though  they  are  withdrawn  from  the  ground  so  as  to  be 
no  longer  functional;  this  animal  seems  to  have  pro- 
ceeded further  along  the  same  line  taken  by  the  hippo- 
potamus. A  deer,  with  still  smaller  rudiments  at  the 
sides  of  its  double  foot,  leads  in  the  comparative  series 
to  the  camel  with  a  cloven  hoof  devoid  of  any  such  relics. 
We  must  pass  with  only  brief  mention  the  lower  orders 
of  mammalia,  like  the  insect-eating  forms  to  which 
armadillos  and  ant-bears  belong.  Of  greater  interest 
are  the  pouched  mammals  like  the  kangaroo  and 
opossums,  which  live  almost  exclusively  in  the  Austrahan 
realm.  The  kangaroo  is  endowed  with  a  head  somewhat 
like  that  of  a  goat,  and  well-developed  hind  legs  that 
enable  it  to  make  leaps  of  astonishing  length.  Some 
of  its  relatives,  such  as  the  bandicoot,  are  hke  rats,  or 
like  bears,  as  in  the  case  of  the  wombat.  The  Tas- 
manian  wolf  is  another  true  marsupial,  even  though 
divergent  adaptation  has  brought  it  to  resemble  the 
carnivora  of  the  dog  tribe  in  general  appearance  and  in 
special  structures  like  the  teeth.  Finally  at  the  very 
bottom  of  the  mammalian  scale  are  two  small  forms 


STRUCTURE  AND   DEVELOPMENT  43 

living  in  the  Australian  faiinal  region.  The  duck  hi  11  or 
Ornithorhy nchus  is  the  hetter  known  animal,  with  its 
close  fur,  webbed  feet,  and  flattened  ducklikf  beak, 
while  its  only  other  near  relative,  the  Echidna,  is 
somewhat  similar  to  the  spiny  hedgehog  in  external 
appearance.  A  unique  peculiarity  of  these  two  forms 
is  that  they  produce  eggs  much  like  those  of  rei)tiles 
and  birds,  and  this  fact,  together  with  others  of  a 
structural  nature,  brings  the  whole  grou])  of  maninials 
near  to  the  lower  classes  of  the  Vertebrata. 

Looking  back  on  the  several  orders  of  mammals,  it 
will  be  seen  that  the  last  mentioned  are  much  Ic.-s 
differentiated  or  specialized  in  their  general  organiza- 
tion. Above  the  level  of  the  egg-layers  and  the  pouched 
mammals,  the  higher  orders  branch  out  in  different 
directions  and  reach  up  to  various  levels  of  the  scale 
of  animal  organization. 

The  foregoing  structural  evidences  of  organic  trans- 
formation in  the  past  histories  of  cats  and  seals  and 
whales  insistently  recall  the  analogies  of  the  locomotive 
and  the  ship  employed  at  the  outset.  All  these  animals, 
like  the  mechanical  examples,  have  come  to  differ  in 
their  derivation  from  the  same  original  parents,  and  their 
lines  of  descent  have  diverged  so  as  to  fit  the  products 
of  evolutionary  modification  to  diverse  circumstances. 
Even  the  vestigial  organs  of  animals  have  their  counter- 
parts in  the  machines.  The  cowcatcher  was  a  large 
and  important  structure  in  the  early  days  of  railroad- 
ing, but  it  has  become  relatively  useless  with  the 
decrease  of  grade  crossings  and  the  construction  of 
more  complete  lines  of  fence.  The  structure  still 
persists,  sometimes  in  a  greatly  reduced  form.     Even 


44  DOCTRINE  OF  EVOLUTION 

more  obvious  is  the  change  of  structure  in  the  case  of 
masts  of  vessels,  which  originally  bore  the  sails  for 
propelling  the  ship.  When  steam  engines  were  em- 
ployed to  give  motive  power,  masts  did  not  disappear. 
They  now  provide  the  derrick  supports  of  trading 
steamers;  in  battleships  their  function  is  changed  to 
that  of  fighting  tops  and  signal  yards.  Even  the  poles 
carried  by  canal  boats  to  bear  windmills  must  be  re- 
garded as  the  reduced  vestiges  of  masts  originally  con- 
structed to  carry  sails;  and  their  adaptive  evolution, 
like  that  of  countless  structures  in  animals,  has  been 
accomplished  by  degeneration. 


The  birds  are  another  class  of  backboned  animals 
which  exhibit  identical  principles  of  relationship.  A 
heron  has  long  legs  and  wide-spreading  toes,  which 
keep  its  body  out  of  the  water  as  it  stalks  about  the 
marshes  where  it  seeks  its  food ;  its  bill  is  a  long  slender 
pincers.  Compare  it  with  an  eagle;  the  latter  has  a 
short  and  heavily  hooked  beak  to  tear  flesh,  while  its 
stout  legs  bear  strongly  curved  talons  to  hold  its 
struggling  prey.  Swimming  birds  like  the  swan  and 
duck  and  loon  possess  feet  which  are  constructed  in 
general  like  those  of  the  former  examples,  but  they  are 
webbed  and  shortened  to  serve  as  paddles.  In  the 
penguin  we  find  a  counterpart  of  the  seal  among 
mammals ;  its  feathers  are  much  reduced  and  its  fore 
limbs  are  no  longer  wings  enabling  the  animal  to  fly, 
but  they  are  paddles  which  it  uses  when  it  swims  in 
pursuit  of  fish.  Finally  the  ostrich  and  wingless  bird 
of  New  Zealand  —  the  Apteryx  —  have  wings  that  are 


STRUCTURE  AND   DEVELOPMENT  45 

useless  vestiges,  which,  in  the  latter  case,  are  hidden 
under  the  brushhke  feathers  covering  the  body.  It 
is  unnecessary  to  add  more  examples,  for  even  these 
few  illustrations  estabhsh  exactly  the  same  i)rincii)les 
of  relationship  and  evidences  of  evolution  that  arc  to 
be  found  in  the  series  of  mammalia. 

Reptiles  also  are  grouped,  like  the  mammals  and  birds, 
as  variations  about  a  central  theme.  An  ordinary  lizard 
is  perhaps  the  nearest  in  form  to  the  remote  ancestor 
from  which  all  have  sprung.  Some  lizards  are  lung 
and  very  slender,  with  all  four  limbs  of  greatly  reduced 
size.  Others,  which  are  still  true  lizards,  have  lost  the 
hind  limbs,  or  even  all  the  legs,  as  in  the  ''blind  worms" 
of  England.  One  step  more,  and  an  animal  which  has 
progressed  further  along  a  similar  line  of  descent 
would  be  a  snake.  Just  as  whales  as  a  group  are 
derivable  from  forms  which  resemble  types  belonging 
to  another  order,  so  snakes  as  an  order  are  to  be  regarded 
as  more  radically  altered  derivatives  of  some  four-footed 
lizardlike  creature.  Alligators  are  very  much  like 
lizards  in  general  form,  and  their  order  is  a  diverging 
branch  from  the  same  limb.  Finally  the  evolution  of 
turtles  from  the  same  ancestors  is  intelligible  if  we  begin 
with  a  short  stout  animal  like  the  so-called  "horned 
toad"  of  Arizona,  and  proceed  to  the  soft-shelled 
tortoise  of  the  Mississippi  River  system  ;  the  establish- 
ment of  a  bony  armor  completes  the  evolution  of  the 
familiar  and  more  characteristic  turtle. 

Frogs  and  salamanders  constitute  another  lower 
class,  called  the  amphibia,  whose  members  are  gilled 
during  the  earlier  stages  of  development.  An  adult 
frog  is  essentially  a  salamander  without  a    tail    and 


46  DOCTRINE   OF  EVOLUTION 

with  highly  developed  hinder  hmbs.  The  salamanders 
differ  as  regards  the  number  of  fishlike  gill  clefts  that 
they  all  possess  in  their  young  stages,  but  which  dis- 
appear entirely  or  in  part  during  later  life.  In  com- 
parison with  the  lizard  as  a  typical  reptile,  a  salamander 
is  more  primitive  in  all  of  its  inner  organic  systems, 
while  in  its  nearly  continuous  body,  with  head  and  tail 
gradually  merging  into  the  trunk,  it  also  displays  a 
somewhat  simpler  form  of  body. 

The  fishes  are  the  lowest  among  the  common  verte- 
brates, and  they  offer  an  abundance  of  independent 
testimony  as  to  the  truth  of  the  principles  of  compara- 
tive anatomy.  The  common  shark  is  perhaps  the  most 
fundamental  form,  with  a  hull-hke  body  undivided  into 
head,  trunk,  and  tail,  and  from  it  have  originated  such 
peculiar  variations  as  the  hammerhead  and  skate. 
Among  fishes  with  true  bones,  a  cod  or  trout  is  the  most 
typical  in  general  features.  Without  ceasing  to  be 
true  bony  fishes,  the  trunk-fish  and  cow-fish  are  adapted 
by  their  peculiar  characters  of  spine  and  armor  plate  to 
repel  many  enemies.  The  puff  fish  can  take  in  a  great 
amount  of  water,  when  disturbed,  so  as  to  become  too 
large  to  be  swallowed  by  some  of  its  foes,  illustrating 
another  adaptive  modification  for  self-defense.  The 
wonderful  colors  and  color  patterns  of  the  tropical 
fish  of  the  reef,  or  of  the  open  water  forms  like  the 
mouse-fish  of  the  Sargossa  Sea,  often  render  them  more 
or  less  completely  hidden  from  the  foraging  enemy.  A 
flounder  looks  like  a  fish  which  was  originally  symmetri- 
cal, but  which  had  come  to  lie  flat  on  its  side  upon  the 
bottom,  whereupon  the  eye  underneath  had  left  its 
original  place  to  appear  on  the  upper  surface.     The 


STRUCTURE  AND   DEVELOPMENT  47 

difficult  and  unusual  conditions  of  deep-sea  existence 
have  been  met  by  fishes  in  two  ways ;  some  forms 
possess  luminous  frilled  and  weedlike  fins,  which 
lure  their  prey  to  within  easy  reach  of  their  jaws,  while 
others  have  enormous  eyes,  so  as  to  make  use  of  all 
possible  rays  of  light  in  their  pursuit  of  food  organisms. 
But  all  of  these  diverse  forms  are  true  Jiislies,  possessing 
a  common  heritage  of  structure  which  demonstrates 
their  unity  of  origin. 

The  brief  review  of  backboned  animals  ha«  shown 
how  comprehensive  are  the  principles  of  relationship. 
The  families  and  tribes  of  each  order,  such  as  the  carniv- 
ora,  are  like  branches  arising  from  a  single  limb;  the 
orders  in  their  turn  exhibit  common  qualities  of  struc- 
ture which  mean  that  they  have  grown  from  the  same 
antecedents,  while  even  the  larger  divisions  or  clasvses 
of  mammals,  birds,  reptiles,  amphibia,  and  fishes,  possess 
a  deep  underlying  theme  whose  dominant  motif  is  the 
backbone,  which  proves  their  ultimate  unity  in  an- 
cestry. The  greater  and  lesser  branches  have  reached 
different  levels,  for  the  fish  is  clearly  simpler  in  its 
make-up  than  the  highly  specialized  bird.  But  the 
great  fact  is  that  structural  evidences  demonstrating 
the  reality  of  genealogical  affinities  are  displayed  by 
the  entire  series  of  vertebrates;  although  they  differ 
much  or  little  in  many  or  fewer  respects  they  have  one 
and  the  same  ground-plan. 


The  lower  animals  devoid  of  backbones,  and  there- 
fore called  invertebrates,  are  not  so  well-known  except 
to  the  student  of  comparative  anatomy,  because  they 


48  DOCTRINE  OF  ^EVOLUTION 

are  not  so  often  met  with,  and  because  they  are  usually 
very  small  or  microscopic ;  but  in  many  respects  their 
importance  to  the  evolutionist  surpasses  that  of  the 
vertebrates.  Their  structural  plans  are  far  more 
varied,  and  they  range  more  widely  from  higher  and 
relatively  complicated  organisms  to  the  unitary  one- 
celled  animals.  A  knowledge  of  some  of  them  is  es- 
sential for  our  present  purpose,  which  is  to  learn  how 
sure  is  the  basis  for  the  principles  of  relationship  and 
how  complete  is  the  structural  evidence  of  evolution. 

Worms  are  represented  in  the  minds  of  most  people 
by  the  common  earthworm  or  sandworm.  The  body  in 
either  case  is  made  up  of  a  series  of  segments  or  joints 
which  agree  closely  throughout  the  animal  in  external 
appearance  and  in  internal  constitution.  A  section  of 
the  digestive  tract,  a  pair  of  nerve  centers,  two  funnel- 
like tubes  for  excretion,  and  similar  blood  vessels 
occur  in  each  portion. 

Precisely  similar  features  are  displayed  by  the  Crus- 
tacea, which  seem  to  be  so  different.  Every  one  is 
familiar  with  the  appearance  of  lobsters  and  crabs. 
Even  in  these  animals  the  body  is  composed  of  segments, 
but  these  are  not  like  one  another,  nor  are  they  freely 
movable  throughout  the  body.  Five  are  fused  in  all 
Crustacea  to  make  a  head;  in  lower  members  of  the 
order  the  eight  succeeding  segments  are  free,  but  in 
the  lobster  they  are  joined  together  and  united  with 
the  head.  The  hinder  part  of  this  animal  is  a  long 
abdomen  whose  segments  remain  more  primitive  and 
independent.  But  in  a  crab,  the  whole  plan  has  been 
modified  by  the  shortening  and  broadening  of  the 
head-thorax,   and  by  the  reduction  of  the  abdomen, 


STRUCTURE  AND   DEVELOPMENT  49 

which  is  also  turned  under  the  anterior  part  of  the  body. 
The  internal  organic  systems  are  constructed  upon  a 
worm  plan  with  modifications.  Nearly  every  one  of 
the  segments  bears  one  pair  of  appendages,  which  can 
be  referred  by  their  forked  nature  to  thr  two-parted, 
oarlike  flaps  of  sandworms,  but  the  a])pendages  of 
Crustacea  have  departed  from  their  ])rototypes  in 
functional  respects  and  in  details  of  structure.  TUcy 
are  variously  feelers,  jaws,  legs,  pincers,  and  swimming 
paddles,  evolved  to  serve  different  purposes,  just  as 
the  limbs  of  the  vertebrates  we  have  described  have 
become  variously  arms,  wings,  flippers  and  paddles  in 
apes,  bats,  seals,  and  whales. 

Butterflies,  beetles,  bees,  and  grasshoppers  seem  at 
first  sight  to  be  entirely  different,  even  though  they 
agree  in  being  more  or  less  segmented.  But  all  of  them 
have  heads  with  four  pairs  of  appendages  of  the  same 
essential  plan,  middle  thoracic  regions  of  three  segments 
more  or  less  united,  bearing  three  pairs  of  legs  and 
usually  two  pairs  of  wings,  while  the  hinder  part  is  a 
freely  jointed  abdomen  without  real  limbs.  In  these 
respects  the  countless  varieties  of  insects  agree  so  that 
they  also  like  Crustacea  of  various  kinds  seem  to  have 
been  derived  from  wormlike  animals  with  more  simi)ly 
segmented  bodies.  Indeed  spiders  and  scorpions  and 
their  relatives  of  the  group  arachnida  prove  for  similar 
reasons  to  be  derivatives  of  the  same  original  stock, 
and  own  cousins  of  the  insects. 

In  nearly  every  one  of  the  invertebrate  branches  we 
find  representatives  which  interest  us  chiefiy  because 
they  appear  to  have  reached  their  present  condition 
by   retrograde   evolution.     Barnacles   are  really  crus- 

B 


50      '  DOCTRINE  OF  EVOLUTION 

tacea,  but  they  have  lost  their  eyes  as  well  as  some 
other  structures  that  are  most  useful  in  animals  with 
a  free  existence,  because  they  have  adopted  a  fixed 
mode  of  life,  which  has  also  brought  about  the  loss 
of  the  original  freely  jointed  character  of  the  body. 
A  tapeworm  as  an  example  of  internal  parasites  is 
an  extremely  degenerate  form  which  lacks  a  digestive 
tract,  because  this  is  superfluous  in  an  animal  which 
lives  bathed  in  the  nutrient  fluids  of  its  host.  Compar- 
ing it  in  other  respects  with  other  low  wormlike  crea- 
tures, it  appears  to  be  a  relative  of  pecuhar  simple  worms 
with  complete  organization  and  independence  of  life. 
All  these  degenerate  forms  enlarge  our  conception  of 
adaptation  by  adding  the  essential  point  that  progress 
is  not  always  the  result  of  evolution.  Indeed  we  have 
learned  this  in  the  case  of  vestigial  and  rudimentary 
structures  of  higher  forms  like  whales,  and  now  we  find 
that  entire  animals  may  degenerate  as  a  result  of 
changes  no  less  adaptive  than  progressive  modifications. 
Passing  by  other  invertebrate  groups  made  up  of 
species  arranged  like  higher  animals  in  smaller  and 
larger  branches  according  to  their  degree  of  fundamental 
similarity,  we  arrive  at  a  place  in  the  scale  occupied 
by  two-layer  animals  without  the  highly  developed 
and  clearly  differentiated  organic  systems  of  the  forms 
above.  The  fresh-water  animal  Hydra  exemplifies 
the  creatures  of  this  level,  where  also  we  find  sea- 
anemones  and  the  soft  polyps  which  form  corals  and 
coral  reefs  by  their  combined  skeletons.  Hydra  is  an 
animal  to  which  we  must  return  again  and  again  as  we 
study  one  or  another  aspect  of  organic  evolution.  In 
general  form  it  is  a  hollow  cylinder  closed  at  one  end, 


STRUCTURE  AND   DEVELOPMENT  51 

by  which  it  attaches  itself,  while  at  the  up|)er  end, 
surrounded  by  a  group  of  tentacles,  is  the  mouth  which 
leads  to  the  central  cavity.  The  wall  of  this  simple 
body  is  composed  of  two  layers  of  cells,  between  which 
there  is  a  gelatinous  layer  rarely  invaded  by  cells.  The 
inner  layer  lines  the  central  si)ace  into  which  food 
organisms  are  thrust  by  the  tentacles,  and  it  is  con- 
cerned primarily  with  digestion.  The  outer  layer 
comprises  cells  for  protection  and  sensation  prima- 
rily. Cells  of  both  layers  have  muscular  prolongations 
which  by  their  operation  enable  the  whole  animal  to 
change  its  form  and  to  move  from  one  place  to  another. 

It  may  seem  that  such  an  animal  is  totally  unlike 
any  of  the  higher  and  more  complex  types.  In  certain 
respects,  however,  it  is  identical  with  the  other  forms 
inasmuch  as  it  performs  all  of  the  eight  biological  tasks 
demanded  by  nature.  It  is  also  similar  in  so  far  as 
its  inner  layer,  like  the  innermost  sheet  of  cells  in 
higher  forms,  is  concerned  with  problems  of  taking 
and  preparing  food,  while  the  protective  outer  layer  re- 
sembles in  function  the  outermost  covering  of  all  animals 
higher  in  the  scale.  Beyond  these  a  still  more  funda- 
mental agreement  is  found  in  its  cellular  composition. 

At  the  lower  end  of  the  animal  scale  are  organisms 
which  consist  of  one  cell  and  nothing  more.  Arriaba, 
to  which  we  must  refer  again  and  again,  is  an  example 
of  this  group  which  possesses  an  overwhelming  inij)or- 
tance  to  the  comparative  student  because  the  origins 
of  all  the  characteristics  of  animals  higher  in  the  scale 
are  to  be  found  within  it.  Amoeba  itself  is  a  naked 
mass  of  protoplasm,  about  -^J^  of  an  inch  in  diameter, 
enclosing  a  nucleus.     Its  form  is  not  constant  during 


52  DOCTRINE  OF  EVOLUTION 

activity,  for  fingerlike  processes  called  pseudopodia 
are  pushed  out  tentatively  in  many  directions  to  be 
followed  as  circumstances  direct  by  the  materials  of 
the  whole  cell  body.  Other  protozoa  differ  in  possessing 
constant  forms,  or  in  having  constant  vibratile  pro- 
cesses, or  shells  of  some  kind,  while  in  still  other  cases 
like  individuals  combine  to  make  colonies  which  are 
more  or  less  definite  and  permanent.  Here  at  the  very 
foot  of  the  organic  scale  are  found  animals  which  seem 
to  be  entirely  different  from  those  above.  Upon 
examination  they,  like  Hydra,  prove  to  be  the  same  as 
regards  the  number  and  kind  of  functions  they  perform, 
but  in  structural  regards  their  evolutionary  relation 
to  all  higher  animals  is  indicated  solely  by  the  fact 
that  they  are  cells  composed  of  protoplasm.  Never- 
theless the  principle  which  states  that  resemblance 
means  consanguinity  still  holds  true,  for  cellular  con- 
stitution is  a  unique  possession  of  things  of  the  living 
world,  —  something  which  demonstrates  the  common 
origin  of  all  living  things  just  as  truly  as  the  '^cat-ness'' 
of  our  first  series  of  examples  reveals  for  a  smaller 
group  the  significance  of  likeness  and  the  nature  of 
the  basic  law  of  comparative  anatomy. 


Employing  a  figure  of  speech,  we  have  climbed  down 
the  animal  tree  from  the  higher  regions  where  the 
mammals  belong.  Having  reached  the  very  foot  of 
the  trunk  we  are  in  a  position  to  review  and  summarize 
the  evidences  which  we  have  discovered  all  about  us 
as  we  have  descended.  The  various  examples  we 
have  mentioned  and  the  groups  to  which  they  belong 


STRUCTURE  AND   DEVELOPiMENT  53 

clearly  occupy  different  places  in  the  scale  which  begins 
with  the  protozoa  and  extends  upward  to  the  most 
complicated  and  differentiated  animals.  Hydra  takes 
its  place  above  the  protozoa  for  obvious  structural 
reasons ;  worms  belong  to  a  still  higher  zone,  surpassed 
by  the  more  complex  jointed  animals  Uke  Crustacea 
and  insects.  Far  above  these  are  the  vertebrates, 
among  which  we  have  already  demonstrated  the  occur- 
rence of  different  grades  of  organization,  from  the  fish 
up  to  the  higher  amphibia  and  reptiles,  and  beyond 
in  two  directions  to  the  diverging  birds  and  mammals. 
The  basic  characteristics  of  every  group  in  a  high 
position  may  be  traced  back  to  some  one  or  another 
of  the  divisions  at  a  lower  level,  so  that  the  general 
sequence  of  the  structural  levels  from  low  to  high 
becomes  intelligible  as  the    order  of  their  evolution. 

To  my  mind  the  rudimentary  and  vestigial  structures 
of  animals  are  in  themselves  proof  positive  of  a  natural 
history  of  change.  The  few^  illustrations  can  be  re- 
inforced by  countless  examples  offered  by  every  group 
of  living  animals.  If  such  structures  have  not  evolved 
naturally  by  degenerating  from  more  efficient  counter- 
parts in  ancestors  of  earlier  times,  and  if  they  have 
been  specially  created,  they  are  utterly  meaningless 
and  their  very  existence  is  unreasonable.  If  common 
sense  is  to  be  employed,  they  demonstrate  evolution. 

Everywhere  throughout  the  whole  series  animals 
place  themselves  in  a  treelike  arrangement,  for  in  tlieir 
respective  levels  they  occur  like  leaves  at  the  (muIs  of 
the  hues  of  descent  which  have  led  up  to  them  and 
which  are  comparable  to  the  branches  and  Hmbs 
arising  from  the   trunk   of  a   tree.     Thus   the   major 


54  DOCTRINE  OF  EVOLUTION 

and  minor  divisions  of  animals  do  not  follow  in  the 
order  of  the  rungs  of  a  ladder,  even  though  they  must  be 
assigned  to  different  levels  according  to  the  complexity 
of  their  construction.  The  summary  given  above, 
namely,  that  the  occurrence  of  lower  and  higher  levels 
reveals  an  order  of  evolution,  is  amplified  and  not  con- 
tradicted by  the  statement  that  the  species  of  animals 
are  grouped  in  a  treelike  arrangement.  It  is  the  task 
of  the  evolutionist,  provided  with  all  the  facts  of  com- 
parative anatomy  and  dealing  only  with  the  various 
species  as  separate  leaves,  so  to  speak,  to  reconstruct 
the  now  invisible  but  not  unreal  twigs  and  branches 
and  limbs  of  the  animal  tree,  and  to  show  how  they  have 
diverged  at  one  time  or  another  as  they  have  grown 
and  spread  to  produce  the  species  of  the  present  day. 
This  he  may  do  in  so  far  as  he  may  find  sufficient 
materials  to  enable  him  to  employ  the  methods  of 
comparative  anatomy  and  the  great  natural  principle 
established  by  this  method  —  that  essential  likeness 
means  consanguinity. 


No  evidence  of  evolution  could  be  more  significant 
and  interesting  than  the  results  provided  by  the  com- 
parative study  of  development.  In  the  first  place  it  is 
an  obvious  fact  that  every  living  thing  changes  in  the 
course  of  its  life-history,  and  if  as  an  adult  it  occupies 
a  high  place  in  the  animal  scale,  its  embryological  trans- 
formation is  more  elaborate  and  intricate  than  in  the 
case  of  a  lower  form.  Every  one  knows  that  organisms 
do  develop,  and  yet  I  believe  that  few  appreciate  the 
tremendous  significance  of  the  mere  fact  that  this  is 


STRUCTURE  AND  DEVELOPMENT  55 

true,  while  still  fewer  are  aware  that  the  peculiar 
and  characteristic  early  stages  throujz;!!  which  an 
animal  passes  in  becoming  an  adult  are  even  mure 
striking  than  the  fact  of  development  itself.  We  shall 
learn  something  of  these  earlier  conditions  in  the 
development  of  some  of  our  most  familiar  animals, 
but  at  the  outset  nothing  can  be  more  important  than 
an  appreciation  of  the  first  great  lesson  of  this  depart- 
ment of  natural  history  —  namely  that  organic  trans- 
formation is  real  and  natural.  We  do  not  need  to 
employ  the  methods  of  formal  logic  to  know  that  in 
growing  up  a  human  infant  undergoes  the  changes 
of  childhood  and  adolescence,  that  kittens  become  cats, 
and  that  an  oak  tree  is  produced  by  an  acorn,  for  we 
know  these  things  directly  by  observing  them.  It  is 
natural  for  development  to  take  place  under  normal 
conditions,  and  if  it  does  not,  then  something  has  inter- 
fered with  nature.  Inasmuch  as  *' growing  up"  is 
accomplished  by  the  alteration  of  an  organic  mechanism 
with  one  structure  into  an  individual  with  a  changed 
plan  of  body,  it  is  in  essence  the  actual  jirocess  of 
evolution  which  the  comparative  stuch'  of  grown  ani- 
mals of  to-day  demonstrates  in  the  way  we  have 
learned.  The  study  of  animal  structure  discovei-s 
the  process  of  evolution  because  the  most  reasonable 
interpretation  of  the  similarities  and  minor  dilTerences 
exhibited  everyAvhere  by  the  various  groups  of  animals 
is  that  descent  with  adaptive  and  (Hvergent  modification 
has  taken  place ;  the  result  is  reached  by  inference, 
it  is  true,  but  by  scientific  and  logical  inference. 
With  development  it  is  otherwise.  No  reasoning  is 
necessary   to    tell   us    that   organic    transformation    is 


56  DOCTRINE  OF  EVOLUTION 

a  real  and  a  natural  process.  We  see  it  everywhere 
about  us  and  we  ourselves  have  come  to  be  what  we 
are  by  a  natural  history  of  change.  Can  we  consistently 
deny  that  it  is  possible  for  a  species  to  alter  in  the  long 
course  of  time  when  a  few  brief  weeks  are  sufficient  for 
the  new-laid  egg  of  the  fowl  to  develop  into  a  fledgling  ? 
Many  indeed  strain  at  the  gnat  of  the  longer  process 
in  the  past  when  without  hesitation  they  recognize  the 
real  and  obvious  fact  of  individual  development  in  a 
brief  period. 

I  have  said  that  development  is  a  ^^ natural"  process. 
We  employ  this  word  for  the  familiar  and  everyday 
occurrence  or  thing ;  it  does  not  imply  that  everything 
is  known  about  the  object  or  phenomenon,  because 
science  knows  that  complete  and  final  knowledge  is 
impossible.  We  say  that  it  is  natural  for  rain  to  fall 
to  the  earth,  and  we  speak  of  the  law  of  gravitation 
according  to  which  this  takes  place  as  a  natural  prin- 
ciple, but  it  may  not  have  occurred  to  many  to  inquire 
what  makes  rain  fall  and  why  do  masses  of  matter 
everywhere  behave  toward  one  another  in  the  consistent 
manner  described  by  the  law  in  question.  Sunshine 
is  natural,  but  we  do  not  know  why  light  travels  as  it 
does  from  the  sun  to  the  earth,  and  this  is  another 
question  which,  like  the  inquiry  into  the  ultimate  cause 
of  the  familiar  and  natural  phenomenon  of  gravitation, 
has  not  yet  been  answered.  But  it  is  still  regarded  as 
natural  for  the  rain  to  fall  and  for  the  sun  to  shine. 
In  the  same  way  does  science  view  development,  de- 
noting it  natural  because  it  is  an  ordinary  everyday 
matter.  And  we  are  under  no  more  obligation  to  postu- 
late supernatural  control  for  the  changing  forms  in  the 


STRUCTURE  AND  DEVELOPMENT  -37 

life-history  of  a  chick  or  a  cat  than  we  need  to  assume 
that  gravitation  and  the  radiation  of  li^ht  demand 
immediate  supernatural  direction.  The  embryology 
of  no  form  is  fully  understood  or  described  or  ex]jlained, 
but  no  intelhgent  person  would  be  willing  to  assert 
that  because  complete  knowledge  is  kicking,  it  is 
unnatural  for  organic  transformation  to  take  place 
during  growth.  Whatever  may  be  the  uUimate  origin 
and  nature  of  the  directing  powers  behind  gravitation 
and  development  and  other  phenomena,  we  have 
no  concern  with  such  matters  because  they  cannot  be 
handled  by  scientific  methods  and  one  belief  about  them 
is  on  the  same  plane  with  any  other.  Our  task  is  to 
deal  with  the  everyday  phenomena  of  life  and  the 
production  of  living  species. 


It  is  not  necessary  to  go  far  afield  to  find  an  animal 
which  will  introduce  us  to  the  general  principles  of 
embryology.  In  the  present  instance  as  in  the  case 
of  comparative  anatomy  almost  any  form  will  disclose 
the  meaning  of  development,  for  animate  nature  is 
uniform  and  consistent  in  its  methods  of  operation 
throughout  its  wide  range.  We  shall  begin  with  the 
familiar  frog  which  every  one  knows  is  a  product  of  a 
tadpole  ;  passing  on  to  the  chick  we  will  learn  more  facts 
that  will  enable  us  to  formulate  the  main  principh^  of 
comparative  embryology  in  definite  terms ;  we  will  then 
be  prepared  to  extend  our  survey  so  as  to  include  some- 
what less  famiHar  facts  and  animals  that  are  even  more 
significant  than  the  first  illustrations. 

If  we  should  visit  a  woodland  pond  in  early  spring,  wo 


58  DOCTRINE  OF  EVOLUTION 

would  find  somewhere  among  the  leaves  and  sticks  in 
the  water  large  masses  of  a  clear  jellylike  consistency 
enclosing  hundreds  of  little  black  spheres  about  an 
eighth  of  an  inch  in  diameter.  These  are  the  egg 
masses  and  eggs  of  a  common  frog.  Watching  them 
day  by  day  we  see  the  small  one-celled  egg  spheres 
divide  into  more  and  more  numerous  portions  which 
are  the  daughter-cells,  destined  to  form  by  their  prod- 
ucts the  many  varied  tissues  and  organs  of  the  develop- 
ing larva  and  adult  frog.  After  three  or  four  days  the 
egg  changes  from  its  globular  form  into  an  oval  or 
elliptical  mass,  and  from  one  end  of  this  a  small  knob 
projects  to  become  a  flattened  waving  tail  a  few  days 
later.  On  the  sides  of  the  larger  anterior  portion 
shallow  grooves  make  their  appearance  and  soon  break 
through  from  the  throat  or  pharynx  to  the  exterior  as 
gill-slits.  Shortly  afterwards  the  little  embryo  wriggles 
out  of  its  encasing  coat  of  jelly,  develops  a  mouth,  and 
begins  its  independent  existence  as  a  small  tadpole,  with 
eyes,  nasal  and  auditory  organs,  and  all  other  parts  that 
are  necessary  for  a  free  life.  Thus  the  one-celled  egg 
has  transformed  into  something  that  it  was  not  at  first,, 
and  in  doing  this  it  has  proved  the  possibility  and  the 
reality  of  organic  reconstruction. 

The  tadpole  breathes  by  means  of  its  gills,  and  it  is 
at  first  entirely  devoid  of  the  lungs  which  the  adult 
frog  possesses  and  uses.  When  we  speak  of  the  larval 
respiratory  organs  as  gills  we  imply  that  they  are  like 
the  organs  of  a  fish  which  have  the  same  name ;  they 
are  truly  like  those  of  fishes,  for  the  blood-vessels 
which  go  to  them  are  essentially  the  same  as  in  the  lower 
types  and  they  are  supported  by  simple  skeletal  rods 


STRUCTURE  AND   DEVKLOPMICXT  59 

like  the  gill-bars  of  the  fish.  In  a  word,  ihcy  arc  the 
same  things. 

The  animal  feeds  and  grows  during  the  months  of 
its  first  summer,  and  hibernates  the  following  winter; 
with  the  w^armth  of  spring  it  revives  and  proceeds 
further  along  the  course  of  its  development.  Near 
the  base  of  the  tail  two  minute  legs  grow  out  from  the 
hinder  part  of  the  body,  and  while  these  are  enlarging 
two  front  legs  make  their  appearance  a  httle  behind  the 
gills.  The  tadpole  now  rises  more  freciuently  to  the 
surface  where  it  takes  small  mouthfuls  of  air.  ]\Iean- 
w^hile  great  changes  are  effected  inside  tlio  body  where 
the  various  systems  of  fishlike  organs  become  remodek^d 
into  amphibian  structures.  A  sac  is  formed  from  the 
wall  of  the  esophagus,  and  this  enlarges  and  divides 
to  form  the  two  simple  lungs.  The  legs  increase  in 
size,  the  tail  dwindles  more  and  more,  the  gills  close  up, 
and  soon  the  animal  hops  out  on  land  as  a  complete 
young  frog.  From  this  time  on  it  breathes  by  means 
of  its  lungs  instead  of  gills,  even  though  it  returns  to 
the  water  to  escape  its  foes,  to  seek  its  j)re3',  ami  to 
hibernate  in  the  mud  of  the  lake  bed  during  the  winter 
months. 

All  these  changes  are  familiar  and  natural,  but  until 
science  places  them  and  similar  facts  in  their  proper 
relations  their  significance  is  lost  to  us.  The  tadj)ole  is 
essentially  a  fish  in  its  general  structure  and  mode  of 
life,  even  though  its  heritage  is  such  that  it  can  develop 
into  a  higher  animal.  When  it  does  become  a  frog  it 
proves  beyond  a  doubt  that  tliere  is  no  impassable 
barrier  between  fishes  and  amphibia.  Our  earlier  com- 
parison of  the  structures  of  these  two  classes  of  verte- 


60  DOCTRINE  OF  EVOLUTION 

brates  led  to  the  conclusion  that  the  latter  had  evolved 
from  antecedents  like  the  former,  and  had  thus  followed 
them  upon  the  earth ;  now  that  sequence  seems  to  have 
some  connection  with  the  method  by  which  a  tadpole, 
obviously  not  a  fish  but  nevertheless  actually  fishlike, 
changes  into  a  frog,  a  member  of  a  higher  class  of  verte- 
brates. This  method  is  employed  by  developing  frogs 
apparently  because  it  follows  the  ancestral  order  of 
events,  and  because,  so  to  speak,  the  only  way  a  frog 
knows  how  to  become  a  frog  is  to  develop  from  an  egg 
first  into  a  fishlike  tadpole  and  then  to  alter  itself  as 
its  ancestors  did  during  their  evolution  in  the  past. 
We  begin  to  see,  then,  that  in  addition  to  the  impressive 
fact  of  development  itself,  the  mode  of  organic  trans- 
formation is  far  more  conclusive  evidence  of  evolution, 
because  it  reveals  an  order  of  events  which'  parallels 
the  order  estabhshed  by  comparative  anatomy  as  the 
evolutionary  sequence. 

However  it  is  well  to  review  some  of  the  changes 
by  which  a  chick  comes  into  existence  before  attempt- 
ing to  comprehend  fully  the  fundamental  principle 
of  development  that  the  tadpole's  history  discloses  to 
us.  The  egg  of  a  common  fowl  is  certainly  not  a  chick. 
Within  the  calcareous  shell  are  two  delicate  membranes 
that  enclose  the  white  or  albumen ;  within  this,  swung 
by  two  thickened  cords  of  the  albumen,  is  the  yellow 
yolk  ball  enclosed  by  a  proper  membrane  of  its  own. 
In  the  earliest  condition,  even  before  the  albumen  and 
the  shell  are  added  and  before  the  egg  is  laid,  on  one 
side  of  the  yolk-mass  there  is  a  tiny  protoplasmic  spot 
which  is  at  first  a  single  cell  and  nothing  more.  The 
hen's  egg  is  relatively  enormous,  but  nevertheless,  like 


STRUCTURE  AND   DEVELOPMENT  61 

that  of  the  frog,  it  starts  upon  its  course  of  development 
as  a  single  unitary  biological  element  —  a  cell.  During 
the  earliest  subsequent  hours  the  first  cell  divides  again 
and  again  to  form  a  small  disk  upon  the  surface  of  the 
yolk.  Soon  the  cells  along  the  middle  line  of  this  small 
sheet  become  rearranged  to  make  an  obvious  streak 
or  band,  and  about  this  line  a  simple  tube  is  constructed 
which  is  destined  to  become  the  futui'c  brain  and 
spinal  cord.  The  whole  disk  continues  to  enlarge  by 
further  division  of  its  constituent  elements  so  that  it 
encloses  more  and  more  of  the  yolk  mass,  but  the  little 
chick  itself  is  made  out  of  the  cells  along  the  central 
line  of  the  original  plate,  from  which  it  folds  at  the  sides 
and  in  front  and  behind  so  as  to  lie  somewhat  above 
and  apart  from  the  flatter  enclosing  cell  layers  which 
partly  surround  the  yolk. 

At  the  sides  of  the  primitive  nerve-tube  small  blocks 
of  cells  arise  to  develop  into  primitive  muscles  and  other 
structures.  As  nourishment  is  brought  to  the  embryo 
from  the  surrounding  layers  enclosing  the  nutrient 
yolk,  one  system  after  another  takes  its  shape  and 
builds  its  several  parts  into  organs  which  can  be  rec- 
ognized as  elementary  structures  of  a  chick.  Among 
the  more  interesting  ones  are  small  clefts  or  slits  formed 
in  the  side  walls  of  the  rudimentary  throat  or  j)harynx. 
Blood-vessels  go  forward  from  the  simple  heart  to  run 
up  through  the  intervening  bars  exactly  as  in  the  tadpole 
and  the  fish.  In  brief,  the  young  chick  possesses  a 
series  of  gill-slits,  for  these  structures  are  the  same  in 
essential  plan  and  relations  as  the  clefts  of  tadpoles  and 
fishes.  Does  this  mean  that  even  birds  have  descended 
from    gill-breathing    ancestors?     Science    answers    in 


62  DOCTRINE   OF  EVOLUTION 

the  affirmative,  because  evolution  gives  the  only  reason- 
able explanation  of  such  facts  as  these.  The  case 
seems  different  from  that  of  the  frog,  because  gills 
are  used  by  the  tadpole,  but  gill-slits  and  gill-bars  can 
have  no  conceivable  value  for  the  chick  as  organs 
concerned  with  the  purification  of  the  blood.  None 
the  less,  if  the  transition  from  a  gilled  tadpole  to  the 
adult  with  lungs  means  an  evolution  of  amphibia  from 
fishlike  ancestors,  then  the  change  of  a  chick  embryo 
with  gill-clefts  into  the  fledgling  without  them  is  most 
reasonably  interpreted  as  proof  that  birds  as  well  as 
amphibia  have  had  ancestors  as  simple  as  fishes. 

As  development  progresses  four  small  pads  make 
their  appearance ;  two  of  these  lie  on  either  side  of 
the  body  back  of  the  head  and  the  other  two  arise  near 
the  posterior  end.  They  are  far  from  being  wings  and 
legs,  but  as  day  follows  day  they  become  molded  into 
somewhat  similar  limbs,  as  much  alike  in  general  plan  as 
the  four  legs  of  a  lizard ;  subsequently  the  ones  at  the 
front  change  into  real  wings  and  the  hinder  ones  be- 
come legs.  Meanwhile  the  internal  organs  slowly  trans- 
form from  fishlike  structures  into  things  that  display 
the  characteristics  of  reptilian  counterparts,  and  only 
later  do  they  become  truly  avian.  Last  of  all  the  finish- 
ing touches  are  made,  and  the  whole  creature  becomes  a 
particular  kind  of  a  bird  which  picks  its  way  out  of 
the  shell  and  shifts  for  itself  as  a  chick. 

Only  a  few  of  the  countless  details  have  been  men- 
tioned which  demonstrate  the  resemblance  of  the 
successive  stages  first  to  fishes,  and  later  to  amphibia 
and  reptiles.  We  have  a  wide  choice  of  materials, 
but  even  the  foregoing  brief  list  of  illustrations  shows 


STRUCTURE  AND   DEVELOPMENT  63 

that  the  order  in  which  the  stages  follow  is  the  one 
which  comparative  anatomy  inde])cndently  proves  to 
be  the  order  of  the  evolution  of  fishes,  amphibia,  rep- 
tiles, and  birds.  Why,  now,  should  it  be  necessary  for 
a  developing  bird  to  follow  this  order?  The  answer 
has  been  found  in  the  immense  array  of  em})ry()l()^ical 
facts  that  investigators  have  verified  and  classified, 
that  all  tell  the  same  story.  It  is,  that  birds  have 
arisen  by  evolution  from  ancestors  which  were  really 
as  simple  as  the  members  of  these  lower  classes.  It 
seems  then  that  the  only  way  a  bird  of  to-day  can 
become  itself  is  to  traverse  the  path  along  which  its 
progenitors  had  progressed  in  evolution.  Stating  its 
conclusions  precisely,  science  formulates  the  princi])le 
in  the  following  words:  individual  development  is  a'-^ 
brief  resume  of  the  history  of  the  species  in  past  times, 
or,  more  technically,  ontogeny  recapitulates  phyloijeny. 
To  be  sure,  the  full  history  is  not  reviewed  in  detail, 
for  the  chick  embryo  does  not  actually  swim  in  water 
and  breathe  by  means  of  gills.  Only  a  condensed 
account  of  evolution  of  its  kind  is  presented  by  an 
embryo  during  its  development;  as  Iluxlcy  and 
Haeckel  have  put  it,  whole  lines  and  paragra])hs  and 
even  pages  are  left  out ;  many  false  passages  of  a 
later  date  are  inserted  as  the  result  of  peculiar  larval 
and  embryonic  needs  and  adjustments.  But  in  its 
major  statements  and  as  a  general  outline,  the  account 
is  a  trustworthy  natural  document  sui)niitted  ai>  evi- 
dence that  higher  species  of  to-day  have  evolved  from 
ancestors  which  must  have  been  like  some  of  the  prc^nt 
lower  animals. 

Coming  now  to  the  mammalia,  it  might  seem  that 


64  DOCTRINE  OF  EVOLUTION 

we  have  reached  forms  so  highly  developed  that  they 
would  not  exhibit  the  same  kind  of  developmental 
history,  but  would  have  their  own  mode  of  growing  up. 
This  is  not  so,  for  like  the  adult  fish,  the  larval  tadpole, 
and  the  embryo  chick,  an  embryo  of  a  cat  or  a  man 
is  at  one  time  constructed  with  a  series  of  gill-clefts 
and  with  blood-vessels  and  skeletal  supports  of  fishlike 
nature  that  are  everywhere  associated  with  gills. 
The  embryos  of  wildcats  and  dogs,  rabbits  and  rats, 
pigs,  deer,  and  sheep,  and  of  all  other  mammalia,  possess 
similar  structures.  Thus  they  all  pass  through  a  stage 
which  is  found  also  in  the  development  of  reptiles, 
birds,  and  amphibia,  —  a  stage  which  corresponds  to 
the  fish  throughout  its  life.  Unless  these  facts  mean 
that  the  great  classes  of  vertebrates  have  originated 
together  from  the  same  or  closely  similar  ancestors, 
they  are  unintelligible ;  for  we  cannot  see  why  a  cat  or 
a  chick  should  have  to  be  essentially  fishlike  at  any 
time  unless  this  is  so.  Comparative  anatomy  states 
as  we  have  learned  that  the  amphibia  as  a  class  have 
evolved  from  and  have  out-developed  the  fishes,  that 
reptiles  have  progressed  still  higher,  and  that  birds 
and  mammals  have  originated  from  reptilian  ancestors 
along  roads  that  have  diverged  beyond  the  immediate 
parent  class.  Because  the  members  of  each  class  have 
to  pass  along  the  same  path  trodden  by  their  many 
varied  ancestors,  although  at  express  speed,  as  it  were, 
the  similarity  of  the  earliest  stages  in  their  develop- 
ment is  explained,  for  during  these  periods  they  are 
traversing  a  path  over  which  their  ancestors  passed 
together. 
The  places  where   the  developing  embryos   depart 


STRUCTURE  AND  DEVELOPMENT  Go 

from  the  common  mode  show  where  the  several  divi- 
sions took  leave  of  one  another  in  iheir  evolution,  — 
a  point  that  comes  out  with  great  clearness  when  the 
facts  of  mammalian  development  are  broadly  com- 
pared. The  embryos  of  carnivora  and  rodents  and 
hoofed  animals  are  alike  in  their  earlier  develoj)- 
ment,  and  their  agreement  means  a  community  of 
origin.  At  a  certain  point  the  cat  and  dog  depart 
from  the  common  mode,  but  they  remain  alike  up  to  a 
far  later  stage  than  the  one  in  which  they  are  similar 
to  the  embryos  of  rats  and  sheep.  The  rat  and 
squirrel  and  rabbit,  on  their  part,  remain  together 
until  long  after  they  take  leave  of  the  carnivora  and 
ungulates;  while  the  sheep  and  cattle  and  i)igs  have 
their  own  branch  line,  w^hich  they  follow  in  conij^any 
after  leaving  the  embryos  of  the  other  orders.  The 
reasons  for  these  facts  seem  to  be  that  the  members 
of  the  three  orders  exemplified  have  evolved  from  the 
same  stock,  w^hich  accounts  for  their  embryonic  simi- 
larity for  a  long  time  after  they  collectively  come  to 
differ  from  amphibia  and  reptiles,  while  the  members 
in  each  order  became  differentiated  only  later,  where- 
fore their  embryonic  paths  coincide  for  a  longer  period. 
Thus  the  degree  of  adult  resemblance  which  indicates 
the  closeness  of  relationship  corresponds  with  the  de- 
gree of  embryonic  agreement ;  that  is,  the  cat  and  dog 
are  much  alike  and  their  modes  of  development  are 
essentially  the  same  to  the  latest  stages,  while  the  cat 
and  horse  agree  only  during  the  earliest  and  middle 
stages,  and  their  lines  diverge  before  those  of  the  cat 
and  dog  on  the  one  hand,  or  tliose  of  the  horse  and 
pig  on  the  other. 

p  


66  DOCTRINE  OF  EVOLUTION 

Like  the  fundamental  principle  of  comparative  anat- 
omy in  its  sphere,  the  Law  of  Recapitulation,  formu- 
lated as  a  summary  description  of  the  foregoing  and 
similar  facts,  is  one  that  holds  true  throughout  the  en- 
tire range  of  embryology  and  for  every  division  of  the 
animal  series,  however  large  or  small.  We  have  dis- 
cussed its  broader  application,  and  now  we  may  take 
up  some  of  the  more  or  less  special  cases  mentioned  in 
the  earlier  section  of  the  present  chapter,  to  see  how  it 
may  work  in  detail. 

The  flounder  was  noted  as  a  variant  of  the  fish  theme 
which  seemed  to  be  a  descendant  of  a  symmetrical 
ancestor  because  its  structural  plan  was  like  that  of 
other  bony  fishes.  If  this  be  true,  and  if  in  its  develop- 
ment a  flounder  must  review  its  mode  of  evolution 
as  a  species,  the  young  fish  ought  to  be  symmetrical; 
and  it  actually  is.  The  grotesque  skate  and  hammer- 
head shark  were  demonstrated  to  be  derivatives  of 
a  simpler  type  of  shark ;  their  embryos  are  practically 
indistinguishable  from  those  of  ordinary  dogfish  and 
sharks. 

Among  the  jointed  animals  a  wealth  of  mf^^resting 
material  is  found  by  the  embryologist.  All  crabs 
seemed  to  be  modified  lobsterlike  creatures ;  to  confirm 
this  interpretation,  based  solely  upon  details  of  adult 
structure,  young  crabs  pass  through  a  stage  when  to  all 
intents  and  purposes  they  are  counterparts  of  lobsters. 
Even  the  twisted  hermit  crab,  which  has  a  soft-skinned 
hinder  part  coiled  to  fit  the  curve  of  the  snail  shell 
used  as  a  protection,  is  symmetrical  and  lobster-like 
when  it  is  a  larva. 

Among  the  insects  many  examples  occur  that  are 


STRUCTURE  AND   DEVELOPMENT  07 

already  familiar  to  every  one.  The  egg  of  a  common 
house-fly  hatches  into  a  larva  called  a  maggot ;  in  this 
condition  the  body  destined  to  become  the  vastly  diiler- 
ent  fly  is  composed  of  soft-skinned  segments  very  much 
alike  and  also  similar  to  the  joints  of  a  worm.  Com- 
parative anatomy  demonstrates  that  the  fly  and  all 
other  insects  have  arisen  from  wormlike  ancestors, 
whose  originally  similar  segments  later  diiTcrentiated 
in  various  ways  to  become  the  diverse  segments  of  adult 
insects ;  the  embryonic  history  of  flies  of  to-day  corrob- 
orates these  assertions,  in  so  far  as  every  indivitlual  fly 
actually  does  become  a  wormlike  larva  before  it  changes 
into  the  final  and  complete  adult  insect.  The  other 
kinds  of  insects  are  equally  striking  in  their  life-his- 
tories. All  beetles,  such  as  the  potato  bug  and  June 
bug,  develop  from  grubs  which,  like  the  maggots  of  flies, 
are  similar  to  worms  in  numerous  respects.  Butterflies 
and  moths  pass  through  a  caterpillar  stage  having  even 
more  striking  resemblances  to  worms.  All  the  larva*  of 
insects  are  therefore  like  one  another,  and  like  worms 
also,  in  certain  fundamental  characters  of  internal  and 
external  structure;  so  the  conclusion  that  the  whole 
group  of  insects  has  arisen  by  evolution  from  more 
primitive  ancestors  resembling  the  worms  of  to-day  is 
based  upon  mutually  explanatory  details  of  compara- 
tive anatomy  and  embryology. 


Let  us  now  turn  back  to  some  of  the  earlier  pages  of 
the  embryological  record  which  we  passed  over  in  order 
that  we  might  translate  the  later  portions  dealing  with 
more  famihar  and  intelligible  structures  like  gills.     Be- 


68  DOCTRINE   OF  EVOLUTION 

fore  the  egg  of  the  frog  becomes  an  elHptical  mass  of 
cells,  it  is  at  one  time  a  double-walled  sac  enclosing  a 
central  cavity;  in  this  stage  it  is  called  a  gastrula. 
Tracing  back  the  mode  of  its  formation,  we  find  that  it  is 
produced  from  a  hollow  sphere  of  fewer  cells  that  are 
essentially  alike;  this  stage  also  is  so  important  that 
the  special  term  hlastula  is  applied  to  it.  Still  earlier, 
there  are  fewer  cells  —  128  or  thereabouts,  64,  32,  16, 
8,  4,  2,  and  1.  In  other  words,  the  starting  point  in 
the  development  of  the  frog  is  a  single  biological  unit; 
this  divides  and  its  products  redivide  to  constitute  the 
many-celled  blastula  and  the  double-walled  gastrula. 
All  the  other  animals  we  have  mentioned  begin  like 
the  frog,  as  eggs  which  are  single  cells  and  nothing  more ; 
they  too  pass  on  to  become  blastulse  and  gastrulse, 
similar  to  those  of  the  frog  in  all  essential  respects, 
particularly  as  regards  the  nature  of  the  organs  produced 
by  each  of  the  two  primary  layers,  and  the  mode  of  their 
formation.  Does  the  occurrence  of  blastulse  and  gas- 
trulse  and  one-celled  beginnings  mean  that  the  higher 
animals  composed  of  numerous  and  much  differentiated 
cells  have  evolved  in  company  from  two-layered  saccular 
ancestors  which  were  themselves  the  descendants  of 
spherical  colonies  of  hke  cells,  and  ultimately  of  one- 
celled  animals  ? 

Comparative  anatomy  has  asserted  that  this  is  so, 
as  we  have  already  learned,  for  it  finds  that  adult  ani- 
mals array  themselves  at  different  levels  of  a  scale 
beginning  at  the  bottom  with  the  protozoa,  continuing 
on  to  the  two-layered  animals  hke  Hydra  and  jelly- 
fish and  sea-anemones,  and  then  extending  upwards  to 
the  region  of  the  more  complicated  invertebrates  and 


STRUCTURE  AND  BEVELOPMKXT  G9 

vertebrates.  It  was  difficult  perhaps  to  believe  that 
these  successive  grades  of  organic  structure  indicated 
an  order  of  evolution,  because  it  seemed  impossible 
that  an  animal  so  simple  as  a  protozoan  could  produce 
offspring  with  the  complex  organization  of  a  frog  or  a 
cat,  even  in  long  ages.  But  development  delivers  its 
evidence  relating  to  this  matter  with  telling  and  im- 
pressive force.  How  can  we  doubt  the  possibility  of 
an  evolution  of  higher  animals  from  ancestors  as  simple 
as  Hydra  and  Amoeba  when  a  frog  and  a  cat,  like  all 
other  complicated  organisms,  begin  individual  existence 
as  single  cells,  and  pass  through  gastrula  stages  ?  If  we 
deny  it,  we  contradict  the  evidence  of  our  senses,  fur 
the  development  is  actually  accomplished  by  the  trans- 
formation of  a  single  cell  into  a  double-walled  sac,  and 
of  this  into  different  and  more  intricate  organic  mechan- 
isms. The  process  can  take  place,  for  it  does  take  place. 
Not  until  the  investigator  becomes  familiar  with  a  wide 
range  of  diverse  animals  and  the  peculiar  qualities  of 
their  similar  early  stages,  can  he  estimate  the  tremen- 
dous weight  of  the  facts  of  comparative  embryology. 
Were  the  statement  iterated  and  reiterated  on  every 
page  and  in  every  paragraph,  there  would  be  no  undue 
emphasis  put  upon  the  astounding  fact  that  the  appar- 
ently impassable  gap  between  a  one-celled  animal  like 
Amoeba  and  a  mammal  like  a  cat  is  actually  compassed 
during  the  development  of  the  last-named  organisms 
from  single  cells.  The  occurrence  of  gill-slits  in  the 
embryos  of  Hzards,  birds,  and  mammals  now  seems  a 
small  thing  when  compared  with  the  correspondences 
disclosed  by  the  earliest  stages  of  development.  But 
in  spite  of  their  complexity,  all  the  changes  of  "growing 


70  DOCTRINE  OF  EVOLUTION 

up"  are  explained  and  understood  by  the  simple  for- 
mula that  the  mode  of  individual  development  owes  its 
nature  primarily  to  the  hereditary  influence  of  earlier 
ancestors  back  to  the  original  animals  which  were 
protozoa. 


Embryology  as  a  distinct  division  of  zoology  has  grown 
out  of  studies  of  classification  and  comparative  anatomy. 
Its  beginnings  may  be  found  in  medieval  natural  his- 
tory, for  as  far  back  as  1651  Harvev  had  pointed  oi^t 
that  alHiyin^  thin,g^  originate  from  ^nmpwha.t  ^jjmjjkr 
germSy  the  terse  dictum  bein^  ^^Ex  oyo  omnia."  By  the 
end  of  the  eighteenth  century  many  had  turned  to  the 
study  of  developing  organisms,  though  their  views  by  no 
means  agreed  as  to  the  way  an  adult  was  related  to  the 
egg.  Some,  like  Bonnet,  held  that  the  germ  was  a 
minute  and  complete  replica  of  its  parent,  which  simply 
unfolded  and  enlarged  like  a  bud  to  produce  a  similar 
organism.  Even  if  this  were  true,  little  would  be  gained, 
for  it  would  still  remain  unknown  how  the  germinal 
miniature  originated  to  be  just  what  it  was  conceived 
and  assumed  to  be.  Wolff  was  the  originator  of  the 
view  that  is  now  practically  universal  among  natural- 
ists, namely,  that  development  is  a  real  process  of 
transformation  from  simpler  to  more  complex  condi- 
tions. 

The  subject  of  comparative  embryology  grew  rap- 
idly during  the  nineteenth  century  as  the  field  of  com- 
parative anatomy  became  better  known,  and  when 
naturalists  became  interested  in  animals,  not  only  as 
specific  types,  but  also  as  the  finished  products  of  an 


STRUCTURE  AND   DEVELOPMi:XT  71 

intricate  scries  of  transformations.  Wicn  life-histories 
were  more  closely  compared,  the  meaning  of  the  resem- 
blances between  early  stages  of  diverse  adult  organismf? 
was  read  by  the  same  method  which  in  comparative 
anatomy  finds  that  consanguinity  is  expressed  by  re- 
semblance. The  great  law  of  recapitulation,  stated  in 
one  form  by  Von  Baer  and  more  definitely  b}-  liaeckel 
in  the  terms  employed  in  the  foregoing  sections,  was  for 
a  time  too  freely  used  and  too  rigidl}-  applied  by  natu- 
ralists whose  enthusiasm  clouded  their  judgment.  A 
strong  reaction  set  in  during  the  latter  part  of  the  nine- 
teenth century,  when  attention  was  directed  to  the 
anachronisms  of  the  embryonic  record  and  to  the 
alterations  that  are  the  results  of  larval  or  embryonic 
adaptation  as  short  cuts  in  development.  Neverthe- 
less, it  is  not  seriously  questioned,  I  believe,  that  the 
main  facts  of  a  single  life-history  owe  their  nature  to 
the  past  evolution  of  the  species  to  which  a  given  animal 
belongs. 

Nowadays  the  problems  in  this  well-organized  de- 
partment are  concerned  not  only  with  more  accurate 
accounts  of  the  development  of  animals,  but  also  with 
the  mechanics  of  development,  with  the  relative  value  of 
external  and  internal  influences,  and  above  all  with  the 
physical  basis  of  inheritance.  It  is  clear  that  the 
factors  that  direct  the  development  of  a  wood  frog's 
egg  so  that  it  becomes  a  wood-frog  and  not  a  tree-toad 
must  lie  in  the  egg  itself,  as  derivatives  from  i\w  two 
parent  organisms.  Weismann  and  his  folltnvers  have 
proved  that  a  peculiar  substance  in  the  nuclei  of  the 
egg  and  its  daughter-jiroducts  contains  the  essential 
factors  of  development,  whatever  these  may  be.     K\- 


72  DOCTRINE  OF  EVOLUTION 

periments  dealing  with  the  phenomena  of  heredity 
in  pure  and  mixed  breeds  have  largely  confirmed  Weis- 
mann's  doctrine,  and  they  have  prepared  the  way  for 
a  deeper  investigation  of  the  marvelous  process  of 
biological  inheritance. 

However  much  he  may  be  interested  in  the  details  of 
embryological  science,  the  general  student  of  natural 
history  is  more  concerned  with  the  bearing  of  its  pri- 
mary laws  upon  the  great  problem  of  evolution.  In  the 
foregoing  brief  review  of  the  fundamental  facts  and 
principles  of  this  subject,  the  purpose  has  been  to  show 
how  the  phenomena  of  development  are  viewed  by  men 
of  science,  and  how  they  take  their  place  in  the  doctrine 
of  organic  evolution.  And  it  has  also  been  made  plain 
that  comparative  anatomy  and  comparative  embry- 
ology support  and  supplement  one  another  in  countless 
ways  and  places,  although  each  in  itself  is  a  complete 
demonstration  that  evolution  is  a  real  and  a  natural 
process. 


Ill 

THE   EVIDENCE    OF   FOSSIL   REMAINS 

Few  natural  objects  appeal  to  the  interest  and  imagi- 
nation of  the  student  with  more  force  than  the  frag- 
ments of  animals  and  plants  released  from  the  rocks 
where  they  have  been  entombed  for  ages.  Our  Hves 
are  so  brief  that  it  is  impossible  for  us  to  comprehend 
the  full  duration  of  the  slow  process  which  constructed 
the  burial  shrouds  of  these  creatures  of  long  ago.  We 
try  to  picture  the  earth  and  its  inhabitants  as  they  were 
when  lizards  were  the  highest  forms  of  animals,  and  we 
wonder  how  life  was  lived  in  the  dense  forests  of  the 
coal  age.  Science  can  never  learn  all  about  the  ancient 
history  of  the  earth  and  of  the  organisms  of  bygone 
times ;  yet  it  has  been  able  to  accomphsh  much  through 
its  endeavors  to  reconstruct  the  past,  for  its  method  is 
one  by  which  sure  results  can  always  be  obtained  when- 
ever there  are  definite  facts  with  which  it  can  work. 
In  our  present  study  of  evolution  we  reach  the  point 
when  we  must  examine  the  testimony  of  the  rocks,  and 
the  results  and  methods  of  that  department  of  knowledge 
called  palaeontology,  which  is  concerned  with  fossils  and 
their  interpretation. 

The  word  ''paleontology"  means  literally  the  ''sci- 
ence of  living  things  of  long  ago."  It  deals  directly 
with  the  remains  of  animals  and  plants  found  as  fossils, 

73 


74  DOCTRINE  OF  EVOLUTION 

and  it  interprets  them  through  its  knowledge  of  the 
way  modern  animals  are  constructed  and  of  the  changes 
the  earth's  crust  has  undergone.  A  skull-like  object 
may  be  found  in  a  coal  field  and  may  come  into  the  hands 
of  the  palaeontologist :  from  his  acquaintance  with  the 
head  skeletons  of  recent  types  he  will  be  able  to  assign 
the  extinct  creature  which  possessed  the  skull  to  a  defi- 
nite place  in  the  animal  scale  and  to  understand  its 
nearer  or  wider  affinities  with  other  animals  of  later 
times  and  of  earlier  epochs.  In  doing  these  things 
palaeontology  employs  the  methods  of  comparative 
anatomy  with  which  we  have  now  become  familiar. 
In  the  performance  of  its  other  tasks,  however,  palaeon- 
tology must  work  independently.  It  is  necessary  to 
know  when  a  fossilized  animal  lived,  not  that  its  time 
need  be  measured  by  an  absolute  number  of  a  few 
thousands  or  millions  of  years  antedating  our  own  era, 
for  that  is  impossible.  But  the  important  thing  is  to 
know  its  relative  age,  and  whether  it  preceded  or 
followed  other  similar  animals  of  its  own  group  or  of 
different  divisions.  The  rocks  themselves  must  be 
understood,  how  they  have  been  formed  and  how  they 
are  related  in  mineralogical  nature  and  in  historical 
succession.  Palaeontology  also  deals  with  a  number  of 
subjects  that  are  not  in  themselves  biological,  such  as 
the  combination  of  circumstances  necessary  for  the 
adequate  preservation  of  fossil  relics.  In  so  far  as  it  is 
concerned  with  physical  matters,  as  contrasted  with 
strictly  biological  data,  it  is  one  with  geology.  Indeed, 
the  investigators  in  these  two  departments  must  always 
work  side  by  side  and  render  mutual  assistance  to  one 
another  in  countless  ways,  for  each  division  needs  the 


EVIDENCE  OF  FOSSIL  RE^UINS  75 

results  of  the  other  in  order  to  accomphsh  its  own  dis- 
tinct purposes.  It  must  be  evident  to  every  one  that  it 
is  impossible  to  understand  the  meaning  of  fossils  and 
the  place  of  the  testimony  of  the  rocks  in  the  doctrine 
of  evolution  without  knowing  much  about  the  geolopical 
history  of  the  earth  and  the  influcMices  at  work  in  the 
past.  For  these  reasons  palaeontology  dilTers  somewhat 
from  the  other  divisions  of  zoology  where  direct  observa- 
tion gives  the  materials  for  arrangement  and  study; 
in  this  case  the  individual  data,  that  is,  the  fossil  frag- 
ments themselves,  can  be  made  available  only  through  a 
knowledge  of  their  exact  situations,  of  the  reasons  for 
their  occurrence  in  particular  places  in  the  rock  series 
and  of  the  way  rocks  themselves  are  constructed  and 
worked  over  by  natural  agencies.  Our  task  is  there- 
fore twofold :  certain  physical  matters  of  a  geological 
nature  must  first  be  investigated  before  the  biological 
facts  can  be  described. 

No  doubt  most  people  feel  justified  in  believing  that 
the  whole  doctrine  of  evolution  must  stand  or  fall 
according  to  the  cogency  of  the  pahrontological  evi- 
dences. Plain  common  sense  says  that  the  owners  of 
shelly  or  bony  fragments  found  in  the  dcH^ply-laid 
strata  of  the  earth  must  have  lived  countless  years 
ago,  and  if  the  evolutionist  asserts  that  ]>rimitive  or- 
ganic forms  of  ancient  times  have  produced  changed 
descendants  of  later  times,  it  would  seem  that  f()>-il 
evidence  would  be  supremely  and  overwh(^lniingly 
important.  It  is  true,  of  course,  that  this  evidence  is 
pecuharly  significant,  because  in  some  ways  it  is  more 
direct  than  that  of  the  other  categories  already  outlined. 
But  it  must  not  be  forgotten  that  the  doctrine  is  already 


76  DOCTRINE  OF  EVOLUTION 

securely  founded  upon  the  basic  principles  of  anatomy 
and  embryology.  Science  must  treat  the  data  of  this 
category  by  different  methods  and  must  view  them  in 
different  ways.  Therefore  we  are  interested  in  palaeon- 
tology because  of  the  way  it  tells  the  story  of  evolution 
in  its  own  words,  and  because  we  are  justified  in  expect- 
ing that  its  account  should  include  a  description  of  some 
such  order  of  events  as  that  revealed  by  the  developing 
embryos  of  modern  organisms  and  that  demonstrated 
by  the  comparative  anatomy  of  the  varied  species  of 
adult  animals. 

It  is  true  that  palaeontology  gives  direct  testimony 
about  the  evolutionary  succession  of  animals  in  geo- 
logic time.  But  we  now  know  that  embryology  is 
even  more  direct  in  its  proof  that  organic  transformation 
is  natural  and  real ;  while  at  the  same  time  there  is  a 
completeness  in  the  full  series  of  developmental  stages 
connecting  the  one-celled  egg  with  the  adult  creature 
that  must  be  forever  lacking  in  the  case  of  the  fossil 
sequence  of  species.  If  paragraphs  and  pages  are 
missing  from  the  brief  embryonic  recapitulation,  whole 
chapters  and  volumes  of  the  fossil  series  have  been  lost 
for  all  time.  The  investigators  whose  task  it  has  been 
to  decipher  the  story  of  the  earth's  evolution  have  had 
to  meet  numerous  and  exasperating  difficulties  which 
do  not  confront  the  embryologist  and  anatomist  who 
study  living  materials.  Nevertheless  the  library  of 
palaeontological  documents  is  one  w^hich  has  been 
founded  for  over  a  century,  and  it  has  grown  fast  dur- 
ing recent  decades,  so  that  consistent  accounts  may  now 
be  read  of  the  great  changes  in  organic  life  as  the  earth 
has  altered  and  grown  older.     And  in  all  this  record, 


EVIDENCE   OF   FOSSIL  REMAINS 


/  / 


there  is  not  a  single  line  or  word  of  fact  that  contradicts 
evolution.  What  definite  evidence  there  is  tells  uni- 
formly in  favor  of  the  doctrine,  for  it  is  possible,  in  the 
first  place,  to  work  out  the  order  of  succession  of  many 
of  the  great  groups  of  animals,  and  this  order  is  found 
to  be  the  same  as  that  established  by  the  other  bodies 
of  evidence.  Secondly,  some  fossil  groups  are  aston- 
ishingly complete,  so  that  the  ancient  history  of  a  form 
like  the  horse  can  be  written  with  something  ai)j)roa('hing 
fullness.  Finally,  the  remains  of  certain  animals  have 
been  found  so  situated  in  geological  ways,  and  so  con- 
structed anatomically,  that  the  zoologist  is  justified  in 
denoting  them  "missing  links,"  because  they  seem  to 
have  been  intermediate  between  groups  that  have 
diverged  so  widely  during  recent  epochs  as  to  render 
their  common  ancestry  scarcely  credible. 

With  these  general  results  in  mind,  we  must  now 
become  acquainted  with  such  subjects  as  the  interpre- 
tation of  fossils,  the  causes  for  the  incompleteness  of 
the  series,  the  conditions  for  fossilization,  the  forces  of 
geological  nature,  and  other  matters  that  make  the 
fossils  themselves  intelligible  as  scientific  evidence. 


Many  views  have  been  entertained  regarding  the 
actual  nature  of  the  rehcs  of  antiquity  exhumed  from 
the  rocks  or  exposed  upon  the  surface  by  the  wear  and 
tear  of  natural  agencies.  In  earliest  times  such  things 
were  variously  considered  as  curious  freaks  of  geo- 
logical formation,  as  sports  of  nature,  or  as  the  remains 
of  the  slain  left  upon  the  battle-ground  of  mythical 
Titans.     Some   of   the   Greeks   supposed   that   fossils 


78  DOCTRINE  OF  EVOLUTION 

were  parts  of  animals  formed  in  the  bowels  of  the  earth 
by  a  process  of  spontaneous  generation,  which  had  died 
before  they  could  make  their  way  to  the  surface.  They 
were  sometimes  described  as  the  bones  of  creatures 
stranded  upon  the  dry  land  by  tidal  waves,  or  by  some 
such  catastrophe  as  the  traditional  flood  of  the  scrip- 
tures. In  medieval  times,  and  even  in  our  own  day, 
some  people  who  have  been  opposed  to  the  acceptance 
of  any  portion  of  the  doctrine  of  evolution  have  actually 
defended  the  view  that  the  things  called  fossils  were 
never  the  shells  or  bones  of  animals  living  in  bygone 
times,  but  that  they  only  simulate  such  things  and  have 
been  created  as  such  together  with  the  layers  of  rock 
from  which  they  may  have  been  taken.  If  we  employed 
the  same  arguments  in  dealing  with  the  broken  frag- 
ments of  vases  and  jewelry  taken  from  the  Egyptian 
tombs  or  from  the  buried  ruins  of  Pompeii,  we  would 
have  to  believe  that  such  pieces  were  created  as  frag- 
ments and  that  they  were  never  portions  of  complete 
objects,  just  because  no  one  alive  to-day  has  ever  seen 
the  perfect  vessel  or  bracelet  fashioned  so  long  ago. 
Common  sense  directs  us  to  discard  such  a  fantastic 
interpretation  in  favor  of  the  view  that  fossils  are  what 
they  seem  to  be  —  simply  relics  of  creatures  that  lived 
when  the  earth  was  younger. 

Until  this  common  sense  view  was  adopted  there  was 
no  science  of  palaeontology.  Cuvier  was  the  first  great 
naturalist  to  devote  particular  attention  to  the  mainly 
unrelated  and  unverified  facts  that  had  been  discovered 
before  his  time.  He  was  truly  the  originator  of  this 
branch  of  zoology,  for  he  brought  together  the  observa- 
tions of  earlier  men  and  extended  his  own  studies  widely 


EVIDENCE  OF  FOSSIL  REMAINS  71) 

and  surely,  emphasizing  particularly  the  necessity  for 
noting  carefully  the  geological  situation  of  a  fossil  in 
rocks  of  an  older  or  later  period  of  formation.  His 
great  result  was  the  demonstration  that  many  groups 
of  animals  existed  in  earlier  ages  that  seem  to  have  no 
descendants  of  the  same  nature  to-day,  and  also  that 
many  or  most  of  our  modern  groups  are  not  represented 
in  the  earhest  formed  sedimentary  rocks,  although  th(\se 
recent  forms  possess  hard  parts  which  W(juld  surely  he 
present  somewhere  in  these  levels  if  the  animals  actually 
existed  in  those  times.  But  the  meaning  of  these 
facts  escaped  Cuvier's  mind.  He  was  a  believer  in 
special  creation,  like  Linnaeus  and  all  but  a  few  among 
his  predecessors,  and  he  explained  the  diversity  of 
the  faunas  of  different  geological  times  in  what  seems 
to  us  a  very  simple  and  naive  way.  In  the  beginning, 
he  held,  w^hen  the  world  was  created,  it  was  furnishrtl 
with  a  complete  set  of  animals  and  plants.  Then  some 
great  upheaval  of  nature  occurred  which  overwhehncMl 
and  destroyed  all  living  creatures.  The  Creator  then, 
in  Cuvier's  view,  proceeded  to  construct  a  new  series  of 
animals  and  plants,  which  were  not  identical  with  those 
of  the  former  time,  but  were  created  according  to  tlie 
same  general  working  plans  or  architectural  schemes 
employed  before.  Another  cataclysm  was  suj)pose(l 
to  have  occurred,  which  destroyed  the  second  series  of 
organisms  and  laid  a  new  covering  of  rocks  over  the 
earth's  surface  for  a  subsequent  period  of  relative  quiet ; 
and  so  the  process  was  continued.  By  this  account, 
Cuvier  endeavored  to  reconcile  the  d(K'trine  of  super- 
natural creation  and  intervention  with  the  obvious 
facts  that  organisms  have  differed  at  various  times  in 


80  DOCTRINE  OF  EVOLUTION 

the  earth's  history.  Although  he  saw  that  animals  of 
successive  periods  displayed  similar  structures,  like 
the  skeleton  of  vertebrates,  which  testified  to  some 
connection,  Cuvier  could  not  bring  himself  to  believe 
that  this  connection  was  a  genealogical  one. 

Mainly  through  the  influence  of  the  renowned  Eng- 
lish man  of  science,  Charles  Lyell,  the  students  of  the 
earth  came  to  the  conclusion  that  its  manifold  struc- 
tures had  developed  by  a  slow  and  orderly  process  that 
was  entirely  natural ;  for  they  found  no  evidence  of  any 
sudden  and  drastic  world-wide  remodeling  such  as  that 
postulated  by  the  Cuvierian  hypothesis  of  catastrophe. 
The  battle  waged  for  many  years ;  but  now  naturalists 
believe  that  the  forces  of  nature,  whose  workings  may 
be  seen  on  all  sides  at  the  present  time,  have  recon- 
structed the  continents  and  ocean  beds  in  the  past  in 
the  same  way  that  they  work  to-day.  The  long  name 
of  ^^uniformitarianism"  is  given  to  Ly ell's  doctrine, 
which  has  exerted  an  influence  upon  knowledge  far 
outside  the  department  of  geology.  Darwin  tells  us 
how  much  he  himself  was  impressed  by  it,  and  how  it 
led  him  to  study  the  factors  at  work  upon  organic 
things  to  see  if  he  could  discern  evidence  of  a  biological 
uniformitarianism,  according  to  which  the  past  history 
of  living  things  might  be  interpreted  through  an  under- 
standing of  their  present  lives. 


What,  now,  are  the  reasons  why  the  palseontological 
evidence  is  not  complete  and  why  it  cannot  be  ?  In  the 
first  place  the  seeker  after  fossil  remains  finds  about 
three  fifths  of  the  earth's  surface  under  water  so  that 


EVIDENCE  OF  FOSSIL  REIVLVINS  81 

he  cannot  explore  vast  areas  of  the  present  ocean  beds 
which  were  formerly  dry  land  and  the  homes  of  now- 
extinct  animals.  Thus  the  field  of  investigation  is 
seriously  restricted  at  the  outset,  but  the  naturahst 
finds  his  work  still  more  limited,  in  so  far  as  much  of  the 
dry  land  itself  is  not  accessible.  The  perennial  snows 
of  the  Arctic  region  render  it  impossible  to  make  a 
thorough  search  in  the  frigid  zone,  and  there  are  many 
portions  of  the  temperate  and  torrid  zones  that  are 
equally  unapproachable  for  other  reasons.  "Rut  even 
where  exploration  is  possible,  the  surface  rocks  are  the 
only  ones  from  which  remains  can  be  readily  obtained, 
for  the  layers  formed  in  earher  ages  are  buried  so  deeply 
that  their  contents  must  remain  forever  unknown  in 
their  entirety.  Only  a  few  scratches  upon  the  earth's 
hard  crust  have  been  made  here  and  there,  so  it  is  small 
wonder  that  the  complete  series  of  extinct  organisms 
has  not  been  produced  by  the  palaeontologist. 

A  brief  survey  of  the  varied  groui)s  of  animals  them- 
selves is  sufficient  to  bring  to  hght  many  biological 
reasons  w^hich  account  for  still  more  of  the  vacant 
spaces  in  the  palaeontological  record.  We  would  hardly 
expect  to  find  remains  of  ancient  microscopic  animals 
like  the  protozoa,  unless  they  possessed  shells  or  other 
skeletal  structures  which  in  their  aggregate  might  form 
masses  like  the  chalk  beds  of  Europe.  Jellyfish  and 
w^orms  and  naked  mollusks  are  examjiles  of  the  numerous 
orders  of  lower  animals  having  no  hard  parts  to  be 
preserved,  and  so  all  or  nearly  all  of  the  extinct  sj^ecies 
belonging  to  these  groups  can  never  be  known.  But 
when  an  animal  like  a  clam  dies  its  shell  can  resist  the 
disintegrating   effects   of   bacteria    and    other   organic 

G 


82  DOCTRINE  OF  EVOLUTION 

and  inorganic  agencies  which  destroy  the  soft  parts, 
and  when  a  form  like  a  lobster  or  a  crab,  possessing  a 
body  protected  by  closely  joined  shell  segments,  falls 
to  the  bottom  of  the  sea,  the  chances  are  that  much  of 
the  animal's  skeleton  will  be  preserved.  Thus  it  is 
that  corals,  Crustacea,  insects,  moUusks,  and  a  few  other 
kinds  of  lower  forms  constitute  the  greater  mass  of 
invertebrate  palseontological  materials  because  of  their 
supporting  structures  of  one  kind  or  another.  Perhaps 
the  skeletal  remains  of  the  vertebrates  of  the  past 
provide  the  student  of  fossils  with  his  best  facts,  on 
account  of  the  resistant  nature  of  the  bones  themselves, 
and  because  the  backboned  animals  are  relatively  mod- 
ern ;  then,  too,  the  rocks  in  which  their  remains  occur 
have  not  been  so  much  altered  by  geological  agencies, 
or  buried  so  deeply  under  the  strata  formed  later. 
Of  course  only  the  hardest  kinds  of  shells  would  remain 
as  such  after  their  burial  in  materials  destined  to  turn 
into  rock;  in  the  majority  of  cases,  an  entombed  bone 
is  infiltrated  or  replaced  by  various  mineral  substances 
so  that  in  time  little  or  nothing  of  the  original  thing 
would  remain,  though  a  mold  or  a  cast  would  persist. 
But  even  if  an  animal  of  the  past  possessed  hard 
structures,  it  must  have  satisfied  certain  limited  condi- 
tions to  have  its  remains  prove  serviceable  to  students 
of  to-day.  A  dead  mammal  must  fall  upon  ground  that 
has  just  the  right  consistency  to  receive  it ;  if  the  soil  is 
too  soft,  its  several  parts  will  be  separated  and  scattered 
as  readily  as  though  it  had  fallen  upon  hard  ground 
where  it  would  be  torn  to  pieces  by  carnivorous  ani- 
mals. The  dead  body  must  then  be  covered  up  by  a 
blanket  of  silt  or  sand  like  that  which  would  be  depose-- 


EVIDENCE  OF  FOSSIL  REMAINS  83 

ited  as  the  result  of  a  freshet.  If  a  skeleton  is  too 
greatly  broken  up  or  scattered,  it  may  he  didiciih  or 
even  impossible  for  its  discoverer  to  piece  together  the 
various  fragments  and  assemble  them  in  tlicir  original 
relations.  Very  few  individuals  have  been  so  buried 
and  preserved  as  to  meet  the  conditions  for  the  forma- 
tion of  an  ideal  fossil.  To  realize  how  little  may  be  left 
of  even  the  most  abundant  of  higher  organisms,  we  have 
only  to  recall  that  less  than  a  century  ago  inuuense 
herds  of  bison  and  wild  horses  roamed  the  Western 
plains,  but  very  few  of  their  skulls  or  other  bones  re- 
main to  be  enclosed  and  fossilized  in  future  strata  of 
rocks.  When  we  appreciate  all  these  diilieullies,  both 
geological  and  biological,  we  begin  to  see  ch^arly  why 
the  ancient  lines  of  descent  cannot  be  known  as  we 
know  the  path  and  mode  of  embr3^onic  transformation. 
The  wonder  is  not  that  the  pala^ontological  record  is 
incomplete,  but  that  there  is  any  coherent  and  deeiplier- 
able  record  at  all.  Yet  in  view  of  the  many  and  varied 
obstacles  that  must  be  surmounted  by  the  invest ic^at or, 
and  the  adverse  factors  which  reduce  the  available 
evidence,  the  rapidly  growing  body  of  paheontological 
facts  is  amply  sufficient  for  the  naturalist  to  use  in  for- 
mulating definite  and  conclusive  principles  of  evolution. 


For  the  purposes  of  pala?ontology,  the  most  essential 
data  of  geology  are  those  which  indicate  the  relative 
ages  of  the  strata  that  make  up  the  hard  out(T  crust  of 
the  earth,  for  only  through  them  can  the  order  of  animal 
succession  be  ascertained.  It  does  not  matter  exactly 
hov/  old  the  earth  may  be.     While  it  is  possible  to 


84  DOCTRINE  OF  EVOLUTION 

determine  the  approximate  length  of  time  required  for 
the  construction  of  sedimentary  rocks  hke  those  which 
natural  agencies  are  producing  to-day,  there  are  few 
definite  facts  to  guide  speculation  as  to  the  mode  or 
duration  of  the  process  by  which  the  first  hard  crys- 
talline surface  of  the  earth  was  formed.  But  palaeon- 
tology does  not  care  so  much  about  the  earliest 
geological  happenings,  for  it  is  concerned  with  the 
manifold  animal  forms  that  arose  and  evolved  after  life 
appeared  on  the  globe.  Questions  as  to  the  way  life 
arose,  and  as  to  the  earliest  transformations  of  the 
materials  by  which  the  earth  was  first  formed  are  not 
within  the  scope  of  organic  evolution,  although  they 
relate  to  intensely  interesting  problems  for  the  student 
of  the  process  of  cosmic  evolution. 

According  to  the  account  now  generally  accepted,  the 
original  material  of  the  earth  seems  to  have  been  a 
semi-solid  or  semi-fluid  mass  formed  by  the  condensation 
of  the  still  more  fluid  or  even  gaseous  nebula  out  of 
which  all  the  planets  of  the  solar  system  have  been 
formed  and  of  which  the  sun  is  the  still  fiery  core.  As 
soon  as  the  earth  had  cooled  sufficiently  its  substances 
crystallized  and  wrinkled  to  form  the  first  mountains 
and  ridges ;  between  and  among  these  were  the  basins 
which  soon  filled  with  the  condensing  waters  to  become 
the  earliest  lakes  and  oceans.  The  wear  and  tear  of 
rains  and  snows  and  winds  so  worked  upon  the  surfaces 
of  the  higher  regions  that  sediments  of  a  finer  or  coarser 
character  like  sand  and  mud  and  gravel  were  washed 
down  into  the  lower  levels.  These  sediments  were 
afterwards  converted  into  the  first  rocks  of  the  so-called 
stratified  or  sedimentary  series,  as  contrasted  with  the 


EVIDENCE  OF   FOSSIL   R1:MAIXS  85 

crystalline  or  plutonic  rocks  like  the  original  mass  of 
the  earth  and  the  kinds  forced  to  the  surface  by  vol- 
canic  eruptions.     Later  the  earth   wrinkled  again   in 
various  ways  and  places  so  that  new  ridges  and  moun- 
tains were  formed  with  new  systems  of  lakes  and  oceans 
and  rivers ;   and  again  the  elements  continued  to  erode 
and  partially  destroy  the  higher  masses  and  to  hiy  down 
new  and  later  series  of  sedimentary  rocks  upon  the  old. 
It  seems  scarcely  credible  that  the  apparently  weak 
forces  of  nature  like  those  we  have  mentioned  are  sufTi- 
ciently  powerful  to  work  over  the  massive  crust  of  the 
earth   as  geology  says   they  have.     Our  attention   is 
caught,  as  a  rule,  only  by  the  greater  thing?-:,  like  the 
earthquakes  at  San  Francisco  and  Valparaiso,  and  the 
tidal  waves  and  cyclones  of  the  South  Seas ;  but  the  re- 
sults of  these  sporadic  and  local  catacl^'sms  are  far  less 
than  the  effects  of  the  persistent  everyday  forces  of 
erosion,  each  one  of  w^hich  seems  so  small  and  futile. 
When  we  look  at  the  Rocky  Mountains  with  their  high 
and  rugged  peaks,  it  seems  almost  impossible  that  rain 
and  frost  and  snow  could  ever  break  them  uj)  and  wear 
them  dow^n  so  that  they  w^ould  become  like  the  rounded 
hills  of  the  Appalachian  Mountain  chain,  yet   this  is 
w^hat  will  happen  unless  nature's  ways  suddenly  change 
to  something  which  they  are  not  now.     A  visitor  to  the 
Grand  Canon  of  the  Colorado  sees  a  magnificent  chasm 
over  a  mile  in  depth  and  two  hundred  miles  long  which 
has  actually  been  carved  through  layer  after  layer  of 
solid  rock  by  the  rushing  torrents  of  the  river.     Per- 
haps it  is  easier  to  estimate  the  geological  effects  of  a 
river  in  such  a  case  as  Niagara.     Here  we  find  a  deep 
gorge  below  the  famous  falls,  which   runs  for  twenty 


86  DOCTRINE   OF  EVOLUTION 

miles  or  so  to  open  out  into  Lake  Ontario.  The  water 
passing  over  the  brim  of  the  falls  wears  away  the  edge 
at  a  rate  which  varies  somewhat  according  to  the  harder 
or  softer  consistency  of  the  rocks,  but  which,  since 
1843,  has  averaged  about  104  inches  a  year.  Knowing 
this  rate,  the  length  of  the  gorge,  and  the  character  of 
the  rocky  walls  already  carved  out,  the  length  of  time 
necessary  for  its  production  can  be  safely  estimated.  It 
is  about  30,000  to  40,000  years,  not  a  long  period  when 
the  whole  history  of  the  earth  is  taken  into  account.  A 
similar  length  of  time  is  indicated  for  the  recession  of  the 
Falls  of  St.  Anthony,  of  the  Mississippi  River,  an  agree- 
ment that  is  of  much  interest,  for  it  proves  that  the  two 
rivers  began  to  make  their  respective  cuttings  when  the 
great  ice-sheet  receded  to  the  north  at  the  end  of  the 
Glacial  epoch. 

What  has  become  of  the  masses  washed  away  during 
the  formation  of  these  gorges  ?  As  gravel  and  mud  and 
silt  the  detritus  has  been  carried  to  the  still  waters  of 
the  lower  levels,  to  be  laid  down  and  later  solidified  into 
sandstone  and  slate  and  shale.  All  over  the  continents 
these  things  are  going  on,  and  indefatigable  forces  are 
at  work  that  slowly  but  surely  shear  from  the  surface 
almost  immeasurable  quantities  of  earth  and  rock  to  be 
transported  far  away.  In  some  instances  it  is  possible 
to  find  out  just  how  much  effect  is  produced  in  a  given 
period  of  time,  especially  in  the  case  of  the  great  river 
systems.  For  example,  the  mass  of  the  fine  particles  of 
mud  and  silt  carried  in  a  given  quantity  of  the  water  of 
the  Mississippi  as  it  passes  New  Orleans  can  be  accu- 
rately measured,  and  a  satisfactory  determination  can 
also  be  made  of  the  total  amount  of  water  carried  by  in  a 


EVIDENCE  OF   FOSSIL  REMAINS  87 

year.  From  these  figures  the  amount  of  materials  in 
suspension  discharged  into  the  Gulf  of  Alexico  becomes 
known.  It  is  sufficient  to  cover  one  square  mile  to  the 
depth  of  2G9  feet ;  in  twenty  years  it  is  one  cubic  mile, 
or  five  cubic  miles  in  a  century.  Turning  now  to  the 
other  aspect  of  this  process,  and  the  antecedent  causes 
which  produce  these  effects,  it  appears  thai  the  area  of 
the  Mississippi  River  basin  is  1,147,000  s(iuare  miles  — 
about  one  third  of  the  total  area  of  the  United  States. 
Knowing  this,  and  the  annual  waste  from  its  surface,  it 
is  easy  to  demonstrate  that  it  will  take  6000  years  to 
plane  ofT  an  average  of  one  foot  of  soil  and  rock  from 
the  whole  of  this  immense  area.  Of  course  only  an 
inch  or  a  few  inches  will  be  taken  from  some  regions 
where  the  ground  is  harder  or  rockier,  or  where  little 
rain  falls,  while  many  feet  will  be  washed  away  from 
other  places.  The  waters  of  the  Hoang-ho  come  from 
about  700,000  square  miles  of  country,  from  which  one 
foot  of  soil  is  washed  away  in  1464  years.  The  Ganges 
River,  draining  about  143,000  square  miles,  carries  off 
a  similar  depth  of  eroded  materials  from  its  basin  in 
823  years  !  Should  we  add  to  the  above  figures  those 
that  specify  the  bulk  of  the  chemical  substances  in 
solution  carried  by  these  waters,  the  total  would  be 
even  greater.  We  know  that  in  the  case  of  the  Thames 
River,  calcareous  substances  to  the  amount  of  10.000 
tons  a  year  are  carried  past  London,  and  all  this  mineral 
has  been  dissolved  by  rain-water  from  the  chalky  clilTs 
and  uplands  of  England,  so  that  the  land  has  become 
less  by  this  amount.  Thus  we  learn  that  vast  altera- 
tions are  being  made  in  the  structure  of  great  continents 
by  rain  and  rivers,  as  well  as  by  glaciers  and  other 


88  DOCTRINE  OF  EVOLUTION 

geological  agencies.  And  at  the  same  time  that  old 
strata  are  undergoing  destruction  new  ones  are  in 
process  of  construction  at  other  places,  where  animal 
remains  can  be  embedded  and  preserved  as  fossils.  The 
forces  at  work  seem  weak,  but  they  continue  their  opera- 
tions through  ages  that  are  beyond  our  comprehension 
and  they  accomplish  results  of  world-building  magnitude. 
Thus  the  whole  process  of  geological  construction  is 
such  that  older  exposed  strata  continually  undergo 
disintegration,  but  this  involves  the  destruction  of  any 
fossils  that  they  might  contain.  The  very  forces  that 
preserve  the  relics  of  extinct  animals  at  one  time  undo 
their  work  at  a  later  period.  There  are  many  other 
influences  besides  that  destroy  the  regularity  of  rock 
layers  or  change  their  mineralogical  characters  by  meta- 
morphosis. It  is  easier  to  see  how  volcanic  outbursts 
alter  their  neighboring  territory.  The  intense  sub- 
terranean heat  and  imprisoned  steam  melt  the  deeper 
substances  of  the  earth's  crust,  so  that  these  materials 
boil  out,  as  it  were,  where  the  pressure  is  greatest,  and 
where  lines  of  fracture  and  lesser  resistance  can  be  found. 
Because  so  much  detritus  is  annually  added  to  the 
ocean  floors  —  enough  to  raise  the  levels  of  the  oceans 
by  inches  in  a  century  —  it  is  natural  that  greater 
pressures  should  be  exerted  in  these  areas  than  in  the 
slowly  thinning  continental  regions.  These  are  some 
of  the  reasons  why  volcanoes  arise  almost  invariably 
along  the  shores  or  from  the  floors  of  great  ocean  beds. 
The  chain  that  extends  from  Alaska  to  Chih  within  the 
eastern  shore  of  the  Pacific  Ocean,  and  the  many  hun- 
dreds of  volcanoes  of  the  Pacific  Islands  bring  toi  the 
surface  vast  quantities  of  eruptive  rocks  which  break 


EVIDENCE  OF  FOSSIL   REMAINS  89 

up  and  overlie  the  sedimentary  strata  formed  roRiiIarly 
in  other  ways  and  at  other  times.  The  volcanoes  of  the 
Java  region  alone  have  thrown  out  at  least  lOU  cubic 
miles  of  lava,  cinders,  and  ashes  during  the  last  100  years 
—  twenty  times  the  bulk  of  the  materials  dischar^;od 
into  the  Gulf  of  Mexico  by  the  Mississippi  River  in  the 
same  period  of  time. 

From  these  and  similar  facts,  the  naturalist  finds  how 
agencies  of  the  present  construct  new  rocks  and  alter 
the  old ;  and  so  in  the  light  of  this  knowledge,  he  pro- 
ceeds with  his  task  of  analyzing  the  remote  past,  confi- 
dent that  the  same  natural  forces  have  done  the  work  of 
constructing  the  lower  geological  levels  because  these 
earlier  products  are  similar  to  those  being  formed  to-day. 
After  learning  this  much,  he  must  immediately  under- 
take to  arrange  the  strata  according  to  their  ages.  This 
might  seem  a  difficult  or  even  an  impossible  task,  but 
the  rocks  themselves  provide  him  with  sure  guidance. 


Wherever  a  river  has  graven  its  deep  way  through  an 
area  of  hard  rocks,  as  in  the  case  of  Niagara,  the  walls 
display  on  their  cut  surfaces  a  series  of  lines  and  planes 
showing  that  they  are  superimposed  layers  formed 
serially  by  deposits  that  have  differed  some  or  much  at 
different  times  according  to  the  circumstances  control- 
ling the  erosion  of  their  constituent  particles.  A  layer 
of  several  feet  in  thickness  may  be  composed  of  com- 
pact shale,  while  above  it  will  be  a  zone  of  limestone, 
and  again  above  this  another  layer  of  shale.  Successive 
strata  like  these,  where  they  are  parallel  and  obviously 
undisturbed,  are  evidently  arranged  in  the  order  of  their 


90  DOCTRINE   OF  EVOLUTION 

formation  and  age.  But  by  far  the  most  impressive 
demonstration  of  the  basic  principle  of  geology  em- 
ployed for  the  determination  of  the  relative  ages  of 
rocks  is  the  mighty  Canon  of  the  Colorado.  As  the 
traveler  stands  on  the  winding  rim  of  this  vast  chasm, 
his  eye  ranges  across  13  miles  of  space  to  the  opposite 
walls,  which  stretch  for  scores  of  miles  to  the  right  and 
left ;  upon  this  serried  face  he  will  see  zone  after  zone 
of  yellow  and  red  and  gray  rock  arranged  with  mathe- 
matical precision  and  level  in  the  same  order  as  on  the 
steep  slopes  beneath  him.  Plain  common  sense  tells 
him  that  the  great  sheets  of  rock  stretched  continuously 
at  one  time  between  the  now  separate  walls,  and  that 
the  various  strata  of  sandstone  and  limestone  were 
deposited  in  successive  ages  from  below  upwards  in  the 
order  of  their  exposure.  When  now  he  extends  his 
explorations  to  another  state  like  Utah  or  Wyoming,  he 
may  find  some  but  not  all  of  the  series  exhibited  in  the 
Grand  Caiion,  overlaid  or  underlaid  bv  other  strata 
which  in  their  turn  can  be  assigned  to  definite  places  in 
the  sequence.  By  the  same  method,  the  geologist 
correlates  and  arranges  the  rocks  not  only  of  different 
parts  of  the  same  state,  or  of  neighboring  states,  but 
even  those  of  widely  separated  parts  of  North  America 
and  of  different  continents.  But  he  learns  that  he  must 
refrain  from  over-hasty  conclusions,  for  he  soon  finds 
that  the  sedimentary  rocks  have  not  been  constructed 
at  the  same  rate  in  different  places  during  one  and  the 
same  epoch,  and  that  rocks  formed  even  at  one  period 
are  not  always  identical  in  nature.  But  his  guiding  prin- 
ciple is  sensible  and  reasonable,  and  by  employing  it  with 
due  caution  he  provides  the  palaeontologist  with  the  req- 


EVIDENCE  OF  FOSSIL  REMAINS 


01 


uisite  knowledge  for  his  special  task,  which  is  toarraiiRO 
the  extinct  animals  whose  remains  are  found  as  fossils  of 
various  earth  ages  in  the  order  of  their  succession  in  time. 

Condensed  Table  of  Pal^ontological  Facts 


Years 

Necessary  for 

Formation 

Number  of 

Feet  in 
Thickness 

Geological 
Age 

Geological 

ElKJCH 

Okdeb  or 
Appearance  or 

C'UAKACTEllIiJTlC 

Gnocrs 

Recent 

or 

Quaternary 

^        •<  15         J 

lllll    1 

^.  ca  c  <  u.  5.ja 

5,000,000 

25,000 

Cenozoic 

or 
Tertiary 

Pleistocene 

Pliocene 

Miocene 

Oligocene 

Eocene 

— 

— 

— 

— 

— 

1 

4,000,000 

23,000 

Mesozoic 

or 
Secondary 

Cretaceous 

Jurassic 

Triassic 

( 

21,000,000 

106,000 

PaLTOzoic 

or 

Primary 

Permian 

Carboniferous 

Devonian 

Silurian 

Cambrian 

20,000,000 

30,000 

Azoic          ] 

Archaean 

After  what  seems  an  unduly  long  preixiration.  wo 
now  come  to  the  actual  biological  evidence  of  evolution 
provided  by  the  results  of  this  division  of  zo()logi('al 
science.  But  all  of  the  foregoing  is  fundamentally  part 
of  this  department  of  knowledge  and  it  is  absolutely 
essential  for  any  one  who  desires  to  understand  what 
the  fossils  themselves  demonstrate. 


92  DOCTRINE   OF  EVOLUTION 

The  oldest  sedimentary  rocks  are  devoid  of  fossil 
remains  and  so  they  are  called  the  Azoic  or  Archaean. 
They  comprise  about  30,000  feet  of  strata  which  seem  to 
have  required  at  least  20,000,000  years  for  their  forma- 
tion. This  period  is  roughly  two-fifths  of  the  whole 
time  necessary  for  the  formation  of  all  the  sedimentary 
rocks,  and  this  proportion  holds  true  even  if  the  entire 
period  of  years  should  be  taken  as  100,000,000  instead 
of  50,000,000  or  less.  The  earth  during  this  early  age 
was  slowly  organizing  in  chemical  and  physical  respects 
so  that  living  matter  could  be  and  indeed  was  formed 
out  of  antecedent  substances  —  but  this  process  does 
not  concern  us  here.  The  important  fact  is  that  the 
second  major  period,  called  the  Palaeozoic,  or  ''age  of 
ancient  animals,"  saw  the  evolution  of  the  lowest 
members  of  the  series,  —  the  invertebrates,  —  and  the 
most  primitive  of  the  backboned  animals,  like  fishes  and 
amphibia.  The  rocks  of  this  long  age  include  about 
106,000  feet  of  strata,  demanding  some  21,000,000  or 
22,000,000  years  for  their  deposition.  Thus  it  is  proved 
that  the  invertebrate  animals  were  succeeded  in  time  by 
the  higher  vertebrates,  which  is  exactly  what  the  evi- 
dences of  the  previous  categories  have  shown.  When 
we  remember  that  the  lower  animals  are  devoid  as  a  rule 
of  skeletal  structures  that  might  be  fossilized,  and  when 
we  recall  the  fact  that  the  strata  of  the  palaeozoic  pro- 
vided the  materials  out  of  which  the  upper  layers  were 
formed  afterwards,  we  can  understand  wh}^  the  ancient 
members  of  the  invertebrate  groups  are  not  known  as 
well  as  the  later  and  higher  forms  like  vertebrates.  Yet 
all  the  fossils  of  these  relatively  unfamiliar  creatures 
clearly  prove  that  no  complex  animal  appears  upon  a 


EVIDENCE  OF  FOSSIL   REMAINS  93 

geological  horizon  until  after  some  sini])le  type  belong- 
ing to  a  class  from  which  it  may  have  taken  its  origin  ; 
in  brief,  there  are  no  anachronisms  in  the  record,  wliich 
always  corresponds  with  the  record  written  by  com- 
parative anatomy,  wherever  the  facts  enable  a  compar- 
ison to  be  made. 

But  the  extinct  animals  of  the  third  and  fourth  ages 
are  more  interesting  to  us,  because  there  are  more  of 
them  and  because  they  are  more  like  the  well-known 
organisms  of  our  present  era.  These  two  ages  are 
called  the  Mesozoic  or  Secondary,  and  the  Cenozoic  or 
Tertiary.  The  former  is  so  named  because  it  was  a 
transitional  age  of  animals  that  are  intermediate  in  a 
general  way  between  the  primitive  forms  of  the  i)re- 
ceding  age  and  those  of  the  next  period;  the  latter 
name  means  the  '^ recent-animal"  age,  when  evolution 
produced  not  only  the  larger  groups  of  our  present 
animal  series,  but  also  many  of  the  smaller  branches  of 
the  genealogical  tree  Hke  orders  and  families  to  which 
the  species  of  to-day  belong. 

Confining  our  attention  to  the  large  vertebrate  classes, 
the  testimony  of  the  rocks  proves,  as  we  have  said,  tliat 
fishes  appeared  first  in  what  are  called  the  Silurian  and 
Devonian  epochs,  w^here  they  developed  into  a  ricli 
and  varied  array  of  types  unequaled  in  modern  times. 
At  that  period,  they  were  the  highest  existing  animals  — 
the  '^ lords  of  creation,"  as  it  were.  To  change  the 
figure,  their  branch  constituted  the  top  of  the  animal 
tree  of  the  time,  but  as  other  branches  grew  ujiwards 
to  bear  their  twigs  and  leaves,  as  the  counterparts  of 
species,  the  species  of  the  branch  of  fishes  decreased  in 
number  and  variety,  as  do  the  leaves  of  a  lower  part  of  a 
tree  when  higher  limbs  grow  to  overshadow  them. 


94  DOCTRINE  OF  EVOLUTION 

Following  the  fishes,  the  amphibia  arose  during  the 
coal  age  or  Carboniferous,  usurping  the  proud  position 
of  the  lower  vertebrate  class.  The  reptiles  then  ap- 
peared and  gained  ascendancy  over  the  amphibia,  to 
become  in  the  Mesozoic  age  the  highest  and  most  varied 
of  the  existing  vertebrates.  At  that  time  there  were 
the  great  land  dinosaurs  with  a  length  of  80  feet,  like 
Brontosaurus ;  aquatic  forms  like  Ichthyosaurus  and 
Plesiosaurus,  whose  mode  of  evolution  from  terrestrial 
to  swimming  habits  was  hke  that  of  seals  and  penguins 
of  far  later  eras.  Flying  reptiles  also  evolved,  to  set  an 
example  for  the  bats  of  the  mammalian  class,  for  both 
kinds  of  flying  organisms  converted  their  anterior 
limbs  into  wings,  although  in  different  ways. 

During  the  Triassic  and  Jurassic  periods  of  the  Meso- 
zoic age,  the  first  birds  and  mammals  appeared  to  follow 
out  their  diverging  and  independent  lines  of  descent. 
Palaeontology  makes  it  possible  to  trace  the  origin  and 
development  of  many  of  the  different  branches  that 
grew  out  of  the  mammalian  limb  from  different  places 
and  at  different  times  during  the  Mesozoic  and  the 
following  age,  called  the  Cenozoic,  or  age  of  recent  ani- 
mals. It  is  unnecessary,  however,  for  us  to  review  more 
of  the  details :  the  main  result  is  obvious ;  namely, 
that  the  appearance  of  the  great  classes  of  vertebrates 
is  in  the  order  of  comparative  anatomy  and  embryology. 
Not  only,  then,  is  the  fact  of  evolution  rendered  trebly 
sure,  but  the  general  order  of  events  is  thrice  and  in- 
dependently demonstrated  to  be  one  and  the  same. 
Surely  we  must  see  that  no  reasonable  explanation 
other  than  evolution  can  be  given  for  these  basic  facts 
and  principles 


EVIDENCE  OF   FOSSIL   I11:MAL\S  95 

Turning  now  to  the  second  division  of  pahpontolopical 
evidence,  we  come  to  those  groups  where  abundant 
materials  make  it  possible  to  arrange  the  animals  of 
successive  epochs  in  series  that  may  be  remarkably 
complete.  For  the  reasons  specihed,  liie  backboned 
animals  provide  the  richest  arrays  of  these  series,  and 
such  histories  as  those  of  horses  and  elei)hants  have 
taken  their  places  in  zoological  science  as  clo.ssics. 
But  even  among  the  invertebrates  significant  cases 
may  be  found.  For  example,  hi  one  restricted  locality 
in  Germany  the  shells  of  snails  belonging  to  the  genus 
Paludina  have  been  found  in  superimposed  strata  in  the 
order  of  their  geological  sequence.  The  ample  material 
shows  how  the  several  species  altered  from  age  to  age 
by  the  addition  of  knobs  and  ridges  to  the  surface  of  the 
shell,  until  the  fossils  in  the  latest  rocks  are  far  different 
from  their  ancestors  in  the  lowermost  levels.  Yet  the 
intervening  shells  fill  in  the  gaps  in  such  a  way  as  to 
show  almost  perfectly  how  the  animals  worked  out 
their  evolutionary  history.  This  example  illustrates 
the  nature  of  many  other  known  series  of  mollusks  and 
of  brachiopods,  extending  over  longer  intervals  and 
connecting  more  widely  separated  ages  like  the  Second- 
ary and  the  present  period. 

Since  the  doctrine  of  evolution  and  its  evidences 
began  to  occupy  the  thoughts  of  the  intellectual  wurKi 
at  large,  no  fossil  forms  have  received  more  attention 
than  the  ancient  members  of  the  horse  tribe.  As  we 
have  learned,  a  modern  horse  is  described  by  com- 
parative anatomy  as  a  one-toed  descendant  of  remote 
five-toed  ancestors.  Wlien  the  hoofed  animals  of 
modern  times  were  reviewed  as  subjects  for  compara- 


96  DOCTRINE  OF  EVOLUTION 

tive  anatomical  study,  the  odd-toed  forms  arranged 
themselves  in  a  series  beginning  with  an  animal  like  an 
elephant  with  the  full  number  of  five  digits  on  each 
foot  and  ending  at  the  opposite  extreme  with  the  horse. 
A  reasonable  interpretation  of  these  facts  was  that 
the  animals  with  fewer  toes  had  evolved  from  ancestors 
with  five  digits,  of  which  the  outer  ones  had  progres- 
sively disappeared  during  successive  geological  periods, 
while  the  middle  one  enlarged  correspondingly.  The 
facts  provided  by  palaeontology  sustain  this  contention 
with  absolutely  independent  testimony.  Disregarding 
some  problematical  five-toed  forms  like  Phenacodus,  the 
first  type  of  undoubted  relationship  to  modern  horses 
is  Hyracotherium,  a  little  animal  about  three  feet  long 
that  lived  during  the  Eocene  period  of  the  Cenozoic 
epoch.  Its  forefeet  had  four  toes  each,  and  its  hinder 
limbs  ended  with  three  toes  armed  with  small  hoofs, 
but  one  of  its  relatives  of  the  same  time  has  a  vestige 
of  another  digit  on  the  hind  foot.  By  the  geological 
time  mentioned,  therefore,  the  earliest  true  horses  had 
already  lost  some  of  the  toes  that  their  progenitors 
possessed.  In  the  Miocene  the  extinct  species,  ob- 
viously descended  from  the  Eocene  forms,  had  lost 
more  of  their  toes;  still  higher,  that  is,  in  the  rocks 
formed  during  succeeding  periods  of  time,  the  animals  of 
this  division  are  much  larger  and  each  of  their  feet  has 
only  three  toes,  of  which  the  middle  one  is  the  largest 
while  the  ones  on  the  sides  are  small  and  withdrawn 
from  the  ground  so  as  to  appear  as  useless  vestiges. 
To  produce  modern  horses  and  zebras  from  these 
nearer  ancestors,  few  additional  changes  in  the  structure 
of  the  feet  are  necessary,  for  the  lateral  toes  need  only 


EVIDENCE  OF  FOSSIL  REMAINS  97 

to  become  a  little  more  reduced  and  the  middle  one  to 
enlarge  slightly  to  give  the  one-toed  hnib  of  modern 
types,  with  its  splint-like  vestiges  still  in  evidence  to 
show  that  the  ancestor's  foot  comprised  more  of 
these  terminal  elements.  Comparing  the  animals  of 
successive  periods,  these  and  other  skc'lctal  structures 
demonstrate  that  the  ancestry  of  each  group  of  species 
is  to  be  found  in  the  animals  of  the  preceding  epoch, 
and  that  the  whole  history  of  horses  is  one  of  natural 
transformation,  —  in  a  word,  of  evolution. 

No  less  interesting  in  their  own  way  are  the  remains 
of  other  hoofed  forms  that  lead  down  to  the  elephants 
of  to-day  and  to  the  mammoth  and  mastodon  of  rela- 
tively recent  geologic  times.  Common  sense  would 
lead  to  the  conclusion  that  a  form  like  a  modern  tapir 
was  the  prototype  from  which  these  creatures  have 
arisen,  and  common  sense  would  lead  us  to  expect  that 
if  any  fossils  of  the  ancestors  of  the  modern  group 
of  elephants  occurred  at  all  they  would  be  like  tapirs. 
Thus  a  fossil  of  much  significance  in  this  connection  is 
Moeritheriuvi,  whose  remains  have  been  found  in  the 
rocks  exposed  in  the  Libyan  desert,  for  this  creature 
was  practically  a  tapir,  while  at  the  same  time  its 
characters  of  muzzle  and  tusk  mark  it  as  very  close 
to  the  ancestors  of  the  larger  woolly  elephants  of  later 
geological  times,  when  the  trunk  had  grown  consider- 
ably and  the  tusks  had  become  greatly  prolonged. 
Again  the  fossil  sequence  confirms  the  conclusions 
of  comparative  anatomy,  regarding  the  mode  by  which 
certain  modern  animals  have  evolved. 

The  fossil  deer  of  North  America,  as  well  as  many 
other  even-toed  members  of  the  group  of  manunalia 


98  DOCTRINE  OF  EVOLUTION 

possessing  hoofs,  provide  the  same  kind  of  conclusive 
evidence.  The  feature  of  particular  interest  in  the 
case  of  their  horns,  is  a  correspondence  between  the 
fossil  sequence  and  the  order  of  events  in  the  life-history 
of  existing  species,  —  that  is,  between  the  results  of 
palaeontology  and  of  embryology.  Horns  of  the 
earliest  known  fossil  deer  have  only  two  prongs ;  in 
the  rocks  above  are  remains  of  deer  with  additional 
prongs,  and  point  after  point  is  added  as  the  ancient 
history  of  deer  is  traced  upwards  through  the  rocks  to 
modern  species.  We  know  that  the  life-history  of 
a  modern  species  of  animals  reviews  the  ancestral 
record  of  the  species,  ^and  what  happens  during  the 
development  of  deer  can  be  directly  compared  with 
the  fossil  series.  It  is  a  matter  of  common  knowledge 
that  the  year-old  stag  has  simple  spikes  as  horns,  and 
that  these  are  shed  to  be  replaced  the  following  year 
by  larger  forked  horns.  Every  year  the  horns  are  lost 
and  new  ones  grow  out,  and  become  more  and  more 
elaborately  branched  as  time  goes  on,  thus  giving  a 
series  of  developmental  stages  that  faithfully  repeats 
the  general  order  of  fossil  horns.  Even  Agassiz,who 
was  a  believer  in  special  creation  and  an  opponent 
of  evolution,  was  constrained  to  point  out  many  other 
instances,  mainly  among  the  invertebrata,  where  there 
was  a  like  correspondence  between  the  ontogeny  of 
existing  species  and  their  phylogenetic  history  as 
revealed  by  the  fossil  remains  of  their  ancestors. 


In  the  last  place,  we  must  give  more  than  a  passing 
consideration  to  some  of  the  extinct  types  of  animals 


EVIDENCE  OF  FOSSIL   REMAINS  00 

that  occupy  the  position  of  "hnks"  hot  ween  groups 
now  widely  separated  by  their  divergence  in  evolution 
from  the  same  ancestors.  Perhaps  the  most  famous 
example  is  ArchoBopteryx  found  in  a  series  of  slates 
in  Germany.  This  animal  is  at  once  a  feathered, 
flying  reptile,  and  a  primitive  bird  with  countless 
reptilian  structures.  Its  short  lu^ad  })ossesses  lizard- 
like jaws,  all  of  which  bear  teeth ;  its  wings  comprise  five 
clawed  digits ;  its  tail  is  composed  of  a  long  series  of 
joints  or  vertebrae,  bearing  large  feathers  in  j^airs ; 
its  breastbone  is  flat  and  like  a  plate,  thus  resembling 
that  of  reptiles  and  differing  markedly  from  the 
great  keeled  breastbone  of  modern  flying  birds,  whose 
large  muscles  have  necessitated  the  development 
of  the  keel  for  purposes  of  firm  attachment.  In 
brief,  this  animal  was  close  to  the  ]X)int  where 
reptiles  and  birds  parted  company  in  evolution,  and 
although  it  was  a  primitive  bird,  it  is  in  a  true  sense  a 
'^ missing  link"  between  reptiles  and  the  group  of 
modern  birds.  Other  fossil  forms  like  Hesperornis 
and  Ichthyornis,  whose  remains  occur  in  the  strata  of  a 
later  date,  fill  in  the  gap  between  Archcroptcryx  and 
the  birds  at  the  present  time,  for  among  other  things 
they  possess  teeth  which  indicate  their  origin  fn)m 
forms  like  Archceopteryx,  while  in  other  respects  they 
are  far  nearer  the  birds  of  later  epochs.  That  these 
hnks  are  not  unique  is  proved  by  numerous  other 
examples  known  to  science,  such  as  those  which  connect 
amphibia  and  reptiles,  ancient  reptiles  and  i)riniitive 
mammals,  as  well  as  those  which  come  between  the 
different  orders  of  certain  vertebrate  classes. 

In  summarizing  the  foregoing  facts,  and  the  larger 


100  DOCTRINE  OF  EVOLUTION     . 

bodies  of  evidence  that  they  exemphfy,  we  learn  how 
surely  the  testimony  of  the  rocks  estabhshes  evolution 
in  its  own  way,  how  it  confirms  the  law  of  recapitulation 
demonstrated  by  comparative  embryology,  and  how 
it  proves  that  the  greater  and  smaller  divisions  of 
animals  have  followed  the  identical  order  in  their 
evolution  that  the  comparative  study  of  the  present 
day  animals  has  independently  described. 


The  facts  of  geographical  distribution  constitute 
the  fifth  division  of  zoology,  and  an  independent 
class  of  evidences  proving  the  occurrence  of  evolution. 
This  department  of  zoology  assumed  its  rightful  status 
only  after  the  other  divisions  had  attained  considerable 
growth.  Many  naturalists  before  Darwin  and  Wallace 
and  Wagner  had  noticed  that  animals  and  plants 
were  by  no  means  evenly  distributed  over  the  surface 
of  the  globe,  but  until  the  doctrine  of  evolution  cleared 
their  vision  they  did  not  see  the  meaning  of  these  facts. 
As  in  the  case  of  all  the  other  departments  of  zoology 
the  immediate  data  themselves  are  famihar,  but  because 
they  are  so  obvious  the  mind  does  not  look  for  their 
interpretation  but  accepts  the  facts  at  their  face  value. 
While  the  phenomena  of  distribution  are  no  less  fascinat- 
ing to  the  naturalist,  and  no  less  effective  in  their  dem- 
onstration of  evolution,  their  comprehensive  treatment 
would  demand  more  space  than  the  whole  purpose  of  the 
present  description  of  organic  evolution  would  justify. 
Thus  a  brief  outline  only  can  be  given  of  the  salient 
principles  of  this  subject  in  order  that  their  bearing 
upon  the  problem  of  species  may  be  indicated. 


EVIDENCE  OF  FOSSIL  RLMAIXS  101 

Even  as  children  we  learn  many  facts  of  animal 
distribution;  every  one  knows  tliat  lions  occur  in 
Africa  and  not  in  America,  that  tigers  live  in  Asia 
and  Malaysia,  that  the  jaguar  is  an  inhabitant  of  the 
Brazihan  forests,  and  that  the  American  i)uma  or 
mountain  Hon  spreads  from  north  to  south  and  from 
east  to  west  throughout  the  American  continents. 
The  occurrence  of  differing  human  races  in  widely 
separated  localities  is  no  less  familiar  and  striking, 
for  the  red  man  in  America,  the  Zulu  in  Africa,  the 
Mongol  and  Malay  in  their  own  territories,  display 
the  same  discontinuity  in  distribution  that  is  character- 
istic of  all  other  groups  of  animals  and  of  plants  a.s 
well.  As  our  sphere  of  knowledge  increases,  we  are 
impressed  more  and  more  forcibly  by  the  diversity 
and  unequal  extent  of  the  ranges  occuj)ied  by  the 
members  of  every  one  of  the  varied  divisions  of  the 
organic  world.  Another  fact  which  bec()m(\s  sig- 
nificant only  when  science  calls  our  attention  to  it 
is  the  absence  from  a  land  hke  Australia  of  higher 
mammals  such  as  the  rabbit  of  Europe.  The  hy- 
pothesis of  special  creation  cannot  explain  this  absence 
on  the  assumption  that  the  rabbit  is  unsuited  to  the 
conditions  obtaining  in  the  country  named,  for  when 
the  species  was  introduced  into  Australia  by  man, 
it  developed  and  spread  with  marvelous  rapidity  and 
destructive  effect.  It  may  seem  impossible  that  fact.s 
like  these  could  possess  an  evolutionary  significance, 
but  they  are  actual  examples  of  the  great  nuiss  of  data 
brought  together  by  the  naturalists  who  have  seen  in 
them  something  to  be  interpreted,  and  who  have  soupht 
and  found  an  explanation  in  the  formularies  of  science. 


102  DOCTRINE  OF  EVOLUTION 

The  general  principles  of  distribution  appear  with 
greatest  clearness  when  an  examination  is  made  of 
the  animals  and  plants  of  isolated  regions  like  islands. 
The  Galapagos  Islands  constitute  a  group  that  has 
figured  largely  in  the  hterature  of  the  subject,  partly 
because  Darwin  himself  was  so  impressed  by  what  he 
found  there  in  the  course  of  his  famous  voyage  around  the 
world  in  the  ^'Beagle."  They  form  a  cluster  on  the 
Equator  about  six  hundred  miles  west  of  the  nearest 
point  of  the  neighboring  coast  of  South  America. 
Although  the  lizards  and  birds  that  live  in  the  group 
differ  somewhat  among  themselves  as  one  passes  from 
island  to  island,  on  the  whole  they  are  most  hke  the 
species  of  the  corresponding  classes  inhabiting  South 
America.  Wliy  should  this  be  so  ?  On  the  hypothesis 
of  special  creation  there  is  no  reason  why  they  should 
not  be  more  like  the  species  of  Africa  or  Austraha  than 
like  those  of  the  nearest  body  of  the  mainland.  The 
explanation  given  by  evolution  is  clear,  simple,  and 
reasonable.  It  is  that  the  characteristic  island  forms 
are  the  descendants  of  immigrants  which  in  greatest 
probability  would  be  wanderers  from  the  neighboring 
continent  and  not  from  far  distant  lands.  Reaching 
the  isolated  area  in  question  the  natural  factors  of 
evolution  would  lead  their  offspring  of  later  generations 
to  vary  from  the  original  parental  types,  and  so  the 
pecuhar  Galapagos  species  would  come  into  being. 
The  fact  that  the  organisms  living  on  the  various 
islands  of  this  group  differ  somewhat  in  lesser  details 
adds  further  justification  for  the  evolutionary  inter- 
pretation, because  it  is  not  probable  that  all  the  isl- 
ands would  be  populated  at  the  same  time  by  similar 


EVIDENCE  OF  FOSSIL  REMAINS  103 

stragglers  from  the  miiinland.  T\\r  first  settlors  in 
one  place  would  send  out  colonies  to  others,  where 
independent  evolution  would  resuh  in  the  appearance 
of  minor  differences  pecuhar  to  the  single  island. 
In  this  manner  science  interprets  the  general  agree- 
ment between  the  animals  of  the  Azores  Islands  and 
the  fauna  of  the  northwestern  ])art  of  Africa,  the 
nearest  body  of  land,  from  which  it  would  be  most 
natural  for  the  ancestors  of  the  island  fauna  to  come. 
The  land-snails  inhabiting  the  various  groups  of 
islands  scattered  throughout  the  vast  extent  of  the 
Pacific  Ocean  provide  the  richest  and  most  ideal  material 
for  the  demonstration  of  the  principles  of  geographical 
distribution.  In  the  Hawaiian  Islands  snails  of  the 
family  of  Achatinellida)  occur  in  great  abundance, 
and  like  the  lizards  of  the  Galapagos  Islands  difT(»rent 
species  occur  on  the  different  members  of  the  grouj). 
Within  the  confines  of  one  and  the  same  island,  they 
vary  from  valley  to  valley,  and  the  correlation  between 
their  isolation  in  geographical  respects  and  specific  dif- 
ferences on  the  other  hand,  first  pointed  out  by  (lulick. 
makes  this  tribe  of  animals  classical  material.  In 
Polynesia  and  Melanesia  are  found  close  n^latives  of 
the  Achatinellida?,  namely,  the  Partuhe,  which  are 
thus  in  relative  proximity  to  the  Achat inellidaD  and 
not  on  the  other  side  of  the  world.  Furthermore, 
the  Partulae  are  not  alike  in  all  of  the  groups  of  Polynesia 
where  they  occur;  the  s])ecics  of  the  Society  Islands 
are  absolutely  distinct  from  those  of  the  Manjuesas, 
Tonga,  Samoan,  and  Solomon  Islands,  although  they 
agree  closely  in  the  basic  characters  that  justify  their 
reference  to  a  single  genus.     The  geological  evidence 


104  DOCTRINE  OF  EVOLUTION 

tells  us  that  these  islands  were  once  the  peaks  of  moun- 
tain ranges  rising  from  a  Pacific  continent  which  has 
since  subsided  to  such  an  extent  that  the  mountain 
tops  have  become  separate  islands.  Thus  the  resem- 
blances between  Hawaiian  and  Polynesian  snails,  and 
the  closer  similarities  exhibited  by  the  species  of  the 
various  groups  of  Polynesia,  are  intelligible  as  the  marks 
of  a  common  ancestry  in  a  widespread  continental 
stock,  while  the  observed  differences  show  the  extent 
of  subsequent  evolution  along  independent  lines  followed 
out  after  the  isolation  of  the  now  separated  islands. 
The  principle  may  be  worked  out  in  even  greater 
detail,  for  it  appears  that  within  the  limits  of  one  group 
diverse  forms  occupy  different  islands,  evolved  in 
different  ways  in  their  own  neighborhoods ;  while 
in  one  and  the  same  island,  the  populations  of  the 
different  valleys  show  marked  effects  of  divergence  in 
later  evolution,  precisely  as  in  the  case  of  the  classic 
Achatinellidae  of  the  Hawaiian  Islands. 

The  broad  and  consistent  principle  underlying  these 
and  related  facts  is  this :  there  is  a  general  cor- 
respondence between  the  differences  displayed  by  the 
organisms  of  two  regions  and  the  degree  of  isolation  or 
proximity  of  these  two  areas.  Thus  the  disconnected 
but  neighboring  areas  of  the  Galapagos  Islands  and 
South  America  support  species  that  resemble  each 
other  closely,  for  the  reasons  given  before ;  long  iso- 
lated areas  like  Australia  and  its  surroundings  possess 
peculiar  creatures  like  the  egg-laying  mammals,  and 
all  of  the  pouched  animals  or  marsupials  with  only 
one  or  two  exceptions  like  our  own  American  opos- 
sum, —  a  correlation   between   a   geological  and  geo- 


EVIDENCE  OF   FOSSIL  RKMAIXS  105 

graphical  discontinuity  on  the  one  hand  and  a  faunal 
peculiarity  on  the  other  that  reinforces  our  confidence 
in  the  evolutionary  interpretation  of  the  facts  of  distri- 
bution. 

It  is  true  that  the  various  classes  of  animals  do  not 
always  appear  with  coextensive  ranges,  llie  barriers 
between  two  groups  of  related  s])ecies  will  not  be  the 
same  in  all  cases.  A  range  like  the  Rocky  Mountains 
will  keep  fresh-water  fish  apart,  while  birds  and  mam- 
mals can  get  across  somewhere  at  some  time.  All 
these  things  must  be  taken  into  account  in  analyzing 
the  phenomena  of  distribution,  and  many  factors  must 
be  given  due  attention ;  but  in  all  cases  the  reasons  for 
the  particular  state  of  affairs  hi  geographical  and 
biological  respects  possess  an  evolutionary  significance. 

Having  then  all  the  facts  of  animal  natural  history 
at  his  disposal,  and  the  uniform  prinei])les  in  each 
body  of  fact  that  demonstrate  evolution,  it  is  small 
wonder  that  the  evolutionist  seems  to  dogmatize  when 
he  asserts  that  descent  with  adaptive  and  divergent 
modification  is  true  for  all  species  of  living  things. 
The  case  is  complete  as  it  stands  to-day,  while  it  is 
even  more  significant  that  every  new  discovery  falls 
into  line  with  what  is  already  known,  and  takes  its 
natural  place  in  the  all-inclusive  doctrine  of  organic 
evolution.  Because  this  explanation  of  the  characteris- 
tics of  the  living  world  is  more  reasonable  than  any 
other,  science  teaches  that  it  is  true. 


IV 

EVOLUTION   AS  A   NATURAL   PROCESS 

The  purpose  of  the  discussions  up  to  this  point  has 
been  to  present  the  reasons  drawn  from  the  principal 
classes  of  zoological  facts  for  believing  that  l  living 
things  have  transformed  naturally  to  become  what  they 
now  are.  Even  if  it  were  possible  to  make  an  ex- 
haustive analysis  of  all  of  the  known  phenomena  of 
animal  structure,  development,  and  fossil  succession, 
the  complete  bodies  of  knowledge  could  not  make  the 
evolutionary  explanation  more  real  and  evident  than 
it  is  shown  to  be  by  the  simple  facts  and  principles 
selected  to  constitute  the  foregoing  outline.  We  have 
dealt  solely  with  the  evidences  as  to  the  fact  of  evolu- 
tion ;  and  now,  having  assured  ourselves  that  it  is 
worth  while  to  so  do,  we  may  turn  to  the  intelligible 
and  reasonable  evidence  found  by  science  which  proves 
that  the  familiar  and  everyday  ^'forces"  of  nature  are 
competent  to  bring  about  evolution  if  they  have 
operated  in  the  past  as  they  do  to-day.  Investigation 
has  brought  to  light  many  of  the  subsidiary  elements 
of  the  whole  process,  and  these  are  so  real  and  obvious 
that  they  are  simply  taken  for  granted  without  a 
suspicion  on  our  part  of  their  power  until  science 
directs  our  attention  to  them. 

For  one  reason  or  another,  those  who  take  up  this 

106 


EVOLUTION   AS  A  NATURAL   PROCESS         107 

subject  for  the  first  time  find  it  difncult  to  haiiish 
from  their  minds  the  idea  that  evohition,  even  if  it  ever 
took  place,  has  been  ended.  Tliey  tiiink  it  futile  to 
expect  that  a  scrutiny  of  to-day's  order  can  j)()ssibly 
find  influences  powerful  enough  to  have  any  share  in 
the  marvelous  process  of  past  evolution  demonstrated 
by  science.  The  naturalists  of  a  century  a^o  held  a 
similar  opinion  regarding  the  earth,  vic^wing  it  a,s  an 
immutable  and  unchanged  product  of  sui)ernatural 
creation,  until  Lyell  led  them  to  see  that  tlie  world  is 
a  plastic  mass  slowly  altering  in  countless  ways,  h 
is  no  more  true  that  living  things  have  ceased  to  evolve 
than  that  mountains  and  rivers  and  glaciers  are  fixed 
in  their  final  forms ;  they  may  seem  everlasting  and 
permanent  only  because  a  human  life  is  so  brief  in 
comparison  with  their  full  histories.  Like  the  develoj)- 
ment  of  a  continent  as  science  describes  it.  tlu^  origin 
of  a  new  species  by  evolution,  its  rise,  culmination, 
and  final  extinction  may  demand  thousands  of  years; 
so  that  an  onlooker  who  is  himself  only  a  conscious 
atom  of  the  turbulent  stream  of  evolving  organic  life 
does  not  live  long  enough  to  observe  more  than  a  small 
fraction  of  the  whole  process.  Therefore  living  species 
seem  unchanged  and  unchangeable  until  a  conviction 
that  evolution  is  true,  and  a  knowledge  of  the  metlind 
of  science  by  which  this  conviction  is  borne  upon  one, 
guide  the  student  onwards  in  the  further  searcli  for 
the  efficient  causes  of  the  process. 

The  biologist  employs  the  identical  methods  used 
by  the  geologist  in  working  out  the  past  history  of 
the  earth's  crust.  The  latter  observ(\s  the  forces  at 
work  to-day,   and   compares   the   new   layers  of  rock 


108  DOCTRINE  OF  EVOLUTION 

now  being  formed  with  the  strata  of  deeper  levels; 
these  are  so  much  alike  that  he  is  led  to  regard  the 
constructive  influences  of  the  past  as  identical  with 
those  he  can  now  watch  at  work.  Similarly  the  biologist 
must  first  learn,  as  we  have  done,  the  principles  of 
animal  construction  and  development,  and  of  other 
classes  of  zoological  facts,  and  then  he  must  turn  his 
attention  from  the  dead  object  of  laboratory  analysis 
to  the  workings  of  organic  machines.  The  way  an 
organism  lives  its  life  in  dynamic  relations  to  the 
varied  conditions  of  existence,  as  well  as  the  mutual 
physiological  relations  of  the  manifold  parts  of  a  single 
organism,  reveal  certain  definite  natural  forces  at  work. 
Therefore  his  next  task  is  to  compare  the  results  ac- 
complished by  these  factors  in  the  brief  time  they  may 
be  seen  in  operation  with  the  products  of  the  whole  pro- 
cess of  organic  evolution,  to  learn,  like  the  geologist  in 
his  sphere,  that  the  present-day  natural  forces  are  able 
to  do  what  reason  says  they  have  done  in  the  past. 
When  the  subject  of  inquiry  was  the  reality  of 
evolution,  it  was  perhaps  surprising  to  find  that  even 
the  most  famihar  animals  like  cats  and  frogs  provided 
adequate  data  for  science  to  use  in  formulating  its 
principles.  So  it  is  with  the  matter  of  method;  it 
is  unnecessary  to  go  beyond  the  observations  of  a  day 
or  a  week  of  human  life  to  find  forces  at  work,  as  real 
and  vital  as  animal  existence  and  organic  life  them- 
selves. This  is  true,  because  evolution  is  true,  and  be- 
cause the  lives  of  all  creatures  follow  one  consistent  law. 
Our  task  is  therefore  much  more  simple  than  most 
people  suppose  it  to  be;  let  us  look  about  us  and 
classify  what  we  may  observe,  increasing  our  knowl- 


EVOLUTION  AS  A  NATURAL  PROCKSS         109 

edge  from   the  wide    array  of    equally  natural   facts 
supplied  by  the  biologist. 

The  analogies  of  the  steamship  and  the  locomotive 
proved  useful  at  many  times  during  tlie  discussion 
of  the  fact  of  evolution,  and  even  in  the  present  con- 
nection they  will  still  be  of  service.  The  evolution 
of  these  dead  machines  has  been  brought  about  by 
man,  who,  as  an  element  of  their  environment,  has 
been  their  creator  as  well  as  the  director  of  their  his- 
torical transformations.  The  result  of  their  changes 
has  been  greater  efficiency  and  better  adjustment 
or  adaptation  to  certain  requirements  fixed  by  man 
himself.  The  whole  process  of  improvement  has  been 
one,  in  brief,  of  trial  and  error;  new  inventions  have 
often  been  worthless,  and  they  have  been  relegated  to 
the  scrap-heap,  while  the  better  part  has  been  finally 
incorporated  in  the  type  machine.  In  brief,  then, 
the  important  elements  in  the  evolution  of  these 
examples  have  been  three;  first,  adaptation,  second, 
the  origination  of  new  parts,  and  third,  the  retention 
of  the  better  invention. 

Are  the  creatures  of  the  living  world  so  constituted 
that  biological  equivalents  of  these  three  essential 
elements  of  mechanical  evolution  can  be  found  ?  Are 
organisms  adapted  to  the  circumstances  controlling 
their  lives,  and  are  they  capable  of  changing  naturally 
from  generation  to  generation,  and  of  transmitting 
their  quahties  to  their  off'spring?  These  are  definite 
questions  that  bring  us  face  to  face  with  the  funda- 
mental problems  relating  to  the  dynamics  or  workings 
of  evolution.  We  need  not  ask  for  or  expect  to  lind 
complete  answers,  for  we  know  that  it  is  impossible 


110  DOCTRINE   OF  EVOLUTION 

to  obtain  them.  But  we  may  expect  to  accomplish 
our  immediate  object,  which  is  to  see  that  evolution 
is  natural.  Our  attention  must  be  concentrated  upon 
the  three  biological  subjects  of  adaptation,  variation, 
and  inheritance,  and  we  must  learn  why  science  describes 
them  as  real  organic  phenomena  and  the  results  of 
natural  causes. 


At  the  very  outset,  when  the  general  characteristics 
of  living  things  were  considered,  much  was  said  on 
the  subject  of  adaptation  as  a  universal  phenomenon 
of  nature.  It  was  not  contended  that  perfection  is 
attained  by  any  living  mechanism,  but  it  was  held  that 
no  place  exists  in  nature  for  an  organism  that  is  in- 
capable of  adjusting  itself  to  the  manifold  conditions 
of  life.  A  modus  vivendi  must  be  established  and  some 
satisfactory  degree  of  adaptation  must  be  attained, 
or  else  an  animal  or  a  species  must  perish.  With 
this  fundamental  point  as  a  basis,  we  look  to  nature 
for  two  kinds  of  natural  processes  or  factors,  first, 
those  which  may  originate  variations  as  primary 
factors,  —  the  counterparts  of  human  ingenuity  and 
invention  in  the  case  of  locomotive  evolution,  —  and 
the  secondary  factors  of  a  preservative  nature  which 
will  perpetuate  the  more  adaptive  organic  changes 
produced  by  the  first  influences;  it  is  clear  that  the 
latter  are  no  less  essential  for  evolution  than  the  first 
causes  for  the  appearance  of  variations. 

The  term  ''variation"  is  employed  for  the  natural 
phenomenon  of  being  or  becoming  different.  It  is  an 
obvious  fact  that  no  child  is  ever  exactly  like  either 


EVOLUTION  AS  A  NATURAL   PROCT-SS  ]  I  1 

of  its  parents  or  like  any  one  of  its  earlier  ancestors  ; 
while  furthermore  in  no  case  does  an  individual  re- 
semble perfectly  another  of  its  own  generation  or 
family.  This  departure  from  the  parental  condition, 
and  the  lack  of  agreement  with  others  even  of  its 
closest  blood-relatives,  are  two  familiar  forms  of 
variation.  As  a  rule,  the  degree  to  which  a  given 
organism  is  said  to  vary  in  a  given  character  is  most 
conveniently  measured  by  the  difference  between  its 
actual  condition  and  the  general  average  of  its  species, 
even  though  there  is  no  such  thing  as  a  specimen  of 
average  nature  in  all  of  its  qualities.  In  brief,  then, 
variation  means  the  existence  of  some  dilTerences 
between  an  individual  and  its  parents,  its  fraternity, 
and,  in  a  wider  sense,  all  others  of  its  species. 

Passing  now  to  the  causes  of  variation,  all  of  the 
countless  deviations  of  living  things  can  be  referred 
to  three  kinds  of  primary  factors ;  namely,  the  environ- 
mental, functional,  and  congenital  influen('(\s  that  work 
upon  the  organism  in  different  ways  and  at  different 
times  during  its  life.  We  shall  learn  that  the  evolu- 
tionary values  of  these  three  classes  are  iiy  no  means 
equal,  but  we  take  a  long  step  forward  wIumi  we  realize 
that  among  the  things  we  see  every  day  are  facts 
demonstrating  the  reality  of  three  kinds  of  natural 
powers  quite  able  to  change  the  characters  of  organic 
mechanisms. 

The  ''environment"  of  an  organism  is  everything 
outside  the  creature  itself.  In  tlie  case  of  an  animal 
it  therefore  includes  other  members  of  its  own  kind, 
and  other  organisms  which  prey  upon  its  species  or 
which  serve  it  as  food,  as  well  as  the  wliole  -enr^s  of 


112  DOCTRINE  OF  EVOLUTION 

inorganic  influences  which  first  come  to  mind  when  the 
term  is  used.  For  example,  the  environment  of  a  Hon 
includes  other  Hons  which  are  either  members  of  its 
own  family,  or  else,  if  they  five  in  the  same  region, 
they  are  its  more  or  less  active  rivals  and  competitors. 
In  the  next  place,  other  kinds  of  animals  exist  whose 
lives  are  intimately  related  to  the  lion's  life,  such  as 
the  antelopes  or  zebras  that  are  preyed  upon,  and  the 
human  hunter  to  whom  the  lion  itself  may  fall  a  victim. 
In  addition,  there  are  the  contrasted  influences  of  inor- 
ganic nature  which  demand  certain  adjustments  of  the 
lion's  activities.  Light  and  darkness,  heat  and  cold,  and 
other  factors  have  their  direct  and  larger  or  smaller 
effects  upon  the  life  of  a  lion,  although  these  effects 
are  less  obvious  in  this  instance  than  in  the  case  of 
lower  organisms. 

The  reahty  of  variations  due  to  the  inorganic  elements 
of  the  environment  is  everywhere  evident.  Those 
who  have  spent  much  time  in  the  sun  are  aware  that 
sunburn  may  result  as  a  product  of  a  factor  of  this 
class.  The  amount  of  sunhght  falling  upon  a  forest 
will  filter  through  the  tree-tops  so  as  to  cause  some 
of  the  plants  beneath  to  grow  better  than  others,  thus 
bringing  about  variations  among  individuals  that  may 
have  sprung  from  the  myriad  seeds  of  a  single  parent 
plant.  In  times  of  prolonged  drought,  plants  cannot 
grow  at  the  rate  which  is  usual  and  normal  for  their 
species,  and  so  many  variations  in  the  way  of  inhibited 
development  may  arise. 

Then  there  are  the  variations  of  a  second  class,  more 
complex  in  nature  than  the  direct  effects  of  environ- 
ment,— namely,  the  functional  results  of  use  and  disuse. 


EVOLUTION   AS,   A  NATURAL   PRUCIl.^^.S  113 

A  blacksmith  uses  his  arm  muscles  more  constantly 
than  do  most  other  men,  and  liis  prolonged  exercise 
leads  to  an  increase  of  his  muscular  capacity.  All 
of  the  several  organic  systems  are  capable  of  consider- 
able development  by  judicious  exercise,  as  every  one 
knows.  If  the  functional  modifications  through  use 
were  unreal,  then  the  routine  of  the  gymnasium  and 
the  schoolroom  would  leave  the  body  and  the  mind  as 
they  were  before.  Furthermore,  we  are  all  familiar 
with  the  opposite  effects  of  disuse.  Paralysis  of  an 
arm  results  in  the  cessation  of  its  growth.  \Mion  a 
fall  has  injured  the  muscles  and  nerves  of  a  child's 
limb,  that  structure  may  fail  to  keep  i)ace  with  the 
growth  of  the  other  parts  of  the  body  as  a  result 
of  its  disuse.  These  are  simple  examples  of  a  wide 
range  of  phenomena  exhibited  everywhere  by  an- 
imals and  even  by  the  human  organism,  demonstrat- 
ing the  plasticity  of  the  organic  mechanism  and 
its  modification  by  functional  primary  factors  of 
variation. 

But  by  far  the  greater  number  of  variations  seem 
to  be  due  to  the  so-called  congenital  causes,  which  are 
sharply  contrasted  with  the  influences  of  tlu»  first 
and  second  classes.  It  is  quite  true  that  the  influences 
of  the  third  class  cannot  be  surely  and  directly  demon- 
strated like  the  others,  but  however  remote  and  vague 
they  themselves  may  appear  to  be,  their  eflects  are 
obvious  and  real,  while  at  the  same  time  their  efTects 
are  to  be  clearly  distinguished  from  the  products  of 
the  other  two  kinds.  Congenital  factors  reside  in 
the  physical  heritage  of  an  organism,  and  their  results 
are   often   evident   before   an   indi\idual   is  subjected 


114  DOCTRINE  OF  EVOLUTION 

to  environmental  influences  and  before  it  begins  to 
use  its  various  organs.  For  example,  it  is  a  matter  of 
common  observation  that  a  child  with  light  hair  and 
blue  eyes  may  have  dark-eyed  and  brown-haired 
parents.  The  fact  of  difference  is  a  phenomenon  of 
variation;  the  causes  for  this  fact  cannot  be  found 
in  any  other  category  than  that  comprising  the 
hereditary  and  congenital  influences  of  parent  upon 
offspring.  How  the  effect  is  produced  by  such  causes 
is  less  important  in  the  present  connection  than  the 
natural  fact  of  congenital  variation.  Science,  however, 
has  learned  much  about  the  causes  in  question,  as  we 
shall  see  at  a  later  point. 

Thus  the  first  step  v/hich  is  necessary  for  an 
evolution  and  transformation  of  organic  mechanisms 
proves  to  be  entirely  natural  when  we  give  only 
passing  attention  to  certain  obvious  phenomena  of 
life.  The  fact  of  ^'becoming  different"  cannot  be 
questioned  without  indicting  our  powers  of  observa- 
tion, and  we  must  believe  in  it  on  account  of  its 
reality,  even  though  the  ultimate  analysis  of  the  way 
variations  of  different  kinds  are  produced  remains  for 
the  future. 

Having  learned  that  animals  are  able  to  change  in 
various  ways,  the  next  question  is  whether  variations 
can  be  transmitted  to  future  generations  through  the 
operation  of  secondary  factors.  Long  ago  Buffon 
held  that  the  direct  effects  of  the  environment  are  im- 
mediately heritable,  although  the  mode  of  this  in- 
heritance was  not  described ;  it  was  simply  assumed 
and  taken  for  granted.  Thus  the  darker  color  of  the 
skin  of  tropical  human  races  would  be  viewed  by  Buffon 


EVOLUTION  AS  A  NATURAL  PROCESS  115 

as  the  cumulative  result  of  the  sun's  din^ct  efTects. 
^jamarck  laid  greater  stress  u|)()n  (he  indirccf  nr  fnnr- 
Lonal  variations  due  to  the  factors  of  us(>  and  disus(>. 
a^d  he  also  assumed  as  self-cvidciij  that  such  cfYccts~ 
w„ere  transmissible  Uti  ''''r'(|iiin>(l  ^'liuractcrs."  Tlii.s 
expression  has  a  technical  significance,  for  it  refers  to 
variations  that  are  added  during  individual  Vifo  to 
the  whole  group  of  hereditary  (luahtics  that  make  any 
animal  a  particular  kind  of  organism.  If  ovohition 
takes  place  at  all,  any  new  kind  of  organism  originating 
from  a  different  parental  type  must  truly  acquire  its 
new  characteristics,  but  few  indeed  of  the  variations 
appearing  during  the  hfetime  of  an  animal  owe  their 
origin  to  the  functional  and  environmental  infhicnces, 
whose  effects  only  deserve  the  name  of  ''acquired 
characters"  in  the  special  biological  sense. 

In  sharp  contrast  to  Lamarckianism,  so  called,  —  al- 
though it  did  not  originate  in  the  mind  of  the  noted 
man  of  science  whose  name  it  bears,  —  is  the  doctrine 
of  natural  selection,  first  proposed  in  its  full  form  l»y 
Charles  Darwin.  This  doctrine  presents  a  wholly 
natural  description  of  the  method  by  which  organisms 
evolve,  putting  all  of  the  emphasis  upon  the  congenital 
causes  of  variation,  although  the  reality  of  other  kinds 
of  change  is  not  questioned.  But  the  contrast  between 
Darwinism  and  the  oilier  descriptions  of  secondary 
factors  can  best  be  made  after  a  somewhat  detailed 
discussion  of  the  former,  which  has  gained  the  adhe- 
rence of  the  majority  of  the  naturalists  of  ttvday. 
However,  we  must  not  pass  on  ^vithout  pointing  out  tliat 
however  much  the  explanations  given  by  various  men 
of  science  may  differ,  they  all  agree  in  expressly  rt^cog- 


116  DOCTRINE  OF  EVOLUTION 

nizing  the  complete  naturalness  of  the  secondary  as 
well  as  of  the  primary  factors  of  evolution. 


The  doctrine  of  natural  selection  forms  the  best 
basis  for  the  detailed  discussion  of  the  way  evolution 
has  come  about  in  the  past  and  how  it  is  going  on 
to-day.  This  is  true  because  it  was  the  first  descrip- 
tion of  nature's  program  to  carry  conviction  to  the 
scientific  world,  and  because  its  major  elements  have 
stood  the  test  of  time  as  no  other  doctrine  has  done. 
Much  has  been  added  to  our  knowledge  of  natural 
processes  during  post-Darwinian  times,  and  new  dis- 
coveries have  supplemented  and  strengthened  the 
original  doctrine  in  numerous  ways,  although  they  have 
corrected  certain  of  the  minor  details  on  the  basis  of 
fuller  investigation. 

At  the  outset  it  must  be  clearly  understood  that 
Darwin's  doctrine  is  concerned  primarily  with  the 
method  and  not  with  the  evidences  as  to  the  actual 
fact  of  evolution.  Most  of  those  who  are  not  familiar 
with  the  principles  of  science  believe  that  Darwin 
discovered  this  process ;  but  their  opinion  is  not  correct. 
The  reality  of  natural  change  as  a  universal  attribute 
of  Hving  things  had  been  clearly  demonstrated  long 
before  Darwin  wrote  the  remarkable  series  of  books 
whose  influence  has  been  felt  outside  the  domains  of 
biology  and  to  the  very  confines  of  organized  knowl- 
edge everywhere.  The  ^^ Origin  of  Species"  was  pub- 
lished in  1859,  and  only  the  last  of  its  fourteen  chapters 
is  devoted  to  a  statement  of  the  evidence  that  evolution 
is  true.     In  this  volume  Darwin  presented  the  results 


EVOLUTION  AS  A  NATURAL  PROCESS         117 

of  more  than  twenty-five  years  of  patient  study  of 
the  phenomena  of  nature,  utiHzing  the  observations 
of  wild  hfe  in  many  regions  visited  by  him  when  he  was 
the  naturahst  of  the  ''Beagle"  during  its  famous  voy- 
age around  the  world.  He  also  considered  at  length 
the  results  of  the  breeder's  work  with  domesticated 
animals,  and  he  showed  for  the  first  time  that  tln^ 
latter  have  an  evolutionary  significance.  Because 
his  logical  assembly  of  wide  series  of  facts  in  this  and 
later  volumes  did  so  much  to  convince  the  intellectual 
world  of  the  reasonableness  of  evolution,  Danvin 
is  usually  and  wrongly  hailed  as  the  founder  of  the 
doctrine.  It  is  interesting  to  note  in  passing  that 
Alfred  Russel  Wallace  presented  a  precisely  similar 
outline  of  nature's  workings  at  about  the  same  time 
as  the  statement  by  Darwin  of  his  theory  of  natural 
selection.  But  Wallace  himself  has  said  that  the 
greater  credit  belongs  to  the  latter  investigator  who 
had  worked  out  a  more  complete  analysis  on  the  ba^is 
of  far  more  extensive  observation  and  research. 

The  fundamental  point  from  which  the  doctrine  of 
natural  selection  proceeds  is  the  fact  that  all  creatures 
are  more  or  less  perfectly  adapted  to  the  circumstances 
which  they  must  meet  in  carrying  on  their  lives  ;  this  is 
the  reason  why  so  much  has  been  said  in  earlier  con- 
nections regarding  the  universal  occurrence  of  organic 
adaptation.  An  animal  is  not  an  independent  thing: 
its  life  is  intertwined  with  the  lives  of  countless  other 
creatures,  and  its  very  living  substance  has  been  buih 
up  out  of  materials  which  with  their  endowments 
of  energy  have  been  wrested  from  the  environment. 
Every   animal,   therefore,   is   engaged    in    an    unceas- 


118  DOCTRINE  OF  EVOLUTION 

ing  struggle  to  gain  fresh  food  and  new  energy, 
while  at  the  same  time  it  is  involved  in  a  many- 
sided  conflict  with  hordes  of  lesser  and  greater 
foes.  It  must  prevail  over  all  of  them,  or  it  must 
surrender  unconditionally  and  die.  There  is  no  com- 
promise, for  the  vast  totality  we  individualize  as  the 
environment  is  stern  and  unyielding,  and  it  never 
relents  for  even  a  moment's  truce. 

To  live,  then,  is  to  be  adapted  for  successful  warfare ; 
and  the  question  as  to  the  mode  of  origin  of  species 
may  be  restated  as  an  inquiry  into  the  origin  of  the 
manifold  adaptations  by  which  species  are  enabled  to 
meet  the  conditions  of  life.  Why  is  adaptation  a 
universal  phenomenon  of  organic  nature  ? 

The  answer  to  this  query  given  by  Darwinism  may 
be  stated  so  simply  as  to  seem  almost  an  absurdity.  It 
is,  that  if  there  ever  were  any  unadapted  organisms, 
they  have  disappeared,  leaving  the  world  to  their  more 
efficient  kin.  Natural  selection  proves  to  be  a  continu- 
ous process  of  trial  and  error  on  a  gigantic  scale,  for 
all  of  living  nature  is  involved.  Its  elements  are  clear 
and  real ;  indeed,  they  are  so  obvious  when  our  attention 
is  called  to  them  that  we  wonder  why  their  effects 
were  not  understood  ages  ago.  These  elements  are 
(1)  the  universal  occurrence  of  variation,  (2)  an  excessive 
natural  rate  of  multipHcation,  (3)  the  struggle  for 
existence  entailed  by  the  foregoing,  (4)  the  consequent 
elimination  of  the  unfit  and  the  survival  of  only  those 
that  are  satisfactorily  adapted,  and  (5)  the  inheritance 
of  the  congenital  variations  that  make  for  success  in 
the  struggle  for  existence.  It  is  true  that  these  elements 
are  by  no  means  the  ultimate  causes  of  evolution,  but 


EVOLUTION   AS   A  NATURAL   PIIOCLSS  119 

their   complexity   does   not   lesson    their   validity   and 
efficiency  as  the  immediate  factors  of  the  process. 


Taking  up  the  first  proposition,  we  return  to  the 
subject  of  variation  that  has  been  discussed  previously 
for  the  purpose  of  demonstrating  its  reahty.  The 
observations  of  every  day  are  enough  to  convince  us 
that  no  two  living  things  are  ever  exactly  alike  in  all 
respects.  The  reason  is  that  the  many  details  of  organic 
structure  are  themselves  variable,  so  that  an  entire 
organism  cannot  be  similar  to  another  either  in  material 
or  in  functional  regards,  while  furtliermore  it  would 
be  impossible  for  an  animal  to  be  related  to  environ- 
mental circumstances  in  the  same  wav  as  another 
member  of  its  species  unless  it  was  possible  for  two 
things  to  occupy  the  same  space  at  the  same  time ! 
Individual  differences  in  physical  constitution  are 
displayed  by  any  litter  of  kittens,  with  identical  i)arents ; 
it  needs  only  a  careful  examination  to  find  the  varia- 
tions in  the  shape  of  the  heads,  the  length  of  their 
tails,  and  in  every  other  character.  Sometimes  the 
differences  are  less  evident  in  physical  (jualities  than 
in  disposition  and  mental  make-up,  for  such  variations 
can  be  found  among  related  kittens  just  as  surely  a.s 
among  the  children  belonging  to  a  single  human  family. 

Not  onl}^  do  all  organisms  vary,  but  they  seem  to 
vary  in  somewhat  similar  ways.  Wliih^  m()d(M*n  investi- 
gations have  thrown  much  light  upon  the  relations  be- 
tween variations  and  their  causes,  of  particular  value 
in  the  case  of  the  congenital  phenomena,  the  greatest 
advance  since  Darwin's  time  consists  in  the  demon- 


120 


DOCTEDsE  OF  EVOLmOX 


siriition  by  the  naturalists  who  have  employed  the 
laborious  methods  of  statistical  analysis  that  the  laws 
according  to  which  differences  occur  are  the  same  where- 
ever  the  facts  have  been  examined.  A  single  illustra- 
tion will  suffice  to  indicate  the  general  natiu^  of  this 
result.  If  the  men  of  a  large  assemblage  should  group 
themselves  according  to  their  different  heights  in  inches, 
we  would  find  that  perhaps  one  half  of  them  would 
agree  in  being  between  five  feet  eight  inches  and  five 
feet  nine  inches  tall.  The  next  largest  groups  would 
be  those  just  below  and  above  this  average  class.  — 
namely,  the  classes  of  five  feet  seven  to  eight  inches 
and  five  feet  nine  to  ten  inches.  Fewer  individuals 
would  be  in  the  groups  of  five  feet  five  to  six  inches  and 
five  feet  ten  to  eleven  inches,  and  still  smaller  numbers 
would  constitute  the  more  extreme  groups  on  opposite 
sides  of  these.  If  the  whole  assemblage  comprised  a 
sufficient  number  of  men,  it  would  be  found  that  a 
class  with  a  given  deviation  fr:™  :i-e  average  in  one 
direction  would  contain  about  the  same  number  of 
individuals  as  the  class  at  the  same  distance  from  the 
average  in  the  opposite  direction.  Taking  into  account 
the  relative  numbers  in  the  several  classes  and  the 
various  degrees  to  which  they  depart  from  the  average, 
the  mathematician  describes  the  whole  phenomenon 
of  variation  in  human  stature  bv  a  concise  formula 
which  outlines  the  so-called  ''curve  of  error."  From 
his  study  of  a  thousand  men,  he  can  tell  how  many 
there  would  be  in  the  various  classes  if  he  had 
the  measurements  of  ten  thousand  individuals,  and 
how  manv  there  would  be  in  the  still  more  ex- 
treme    classes    of    verv    short    and    verv    tall    men 


E\'OLmON  .A^  A  NATTR-^L  PROCESS         121 

which  might  not  be  represented  among  one  thousand 
people. 

It  is  not  possible  to  explain  why  variation  dioiikl 
follow  this  or  any  other  mathematical  law  without 
entering  into  an  unduly  extensive  discussion  of  *^- 
laws  of  error.  The  mathematicians  themselves  leli 
us  in  general  terms  that  the  observations  they  describe 
so  simply  by  their  formulff  :  v  as  the  result  of 
so-called  chance,  by  which  theyme-an  that  the  combined 
operation  of  numerous,  diverse,  and  uncorrelated  factors 
brings  about  this  result,  and  not,  of  course,  that  there 
is  such  a  thing  as  an  uncaused  event  or  phenomepon 

Whenever  any  extensive  series  of  like  oreani^^ms  has 

been  studied  with  reference  to  the  var„. s  of  a 

particular  character,  the  variations  group  themselves  so 
as  to  be  described  by  identical  or  similar  cun-es  of  error. 
It  is  certainly  significant  that  this  is  true  for  such 
diverse  characters,  cited  at  random  from  the  lists  of 
the  Hterature,  as  the  nimiber  of  ray-flowers  of  white 
daisies,  the  ntunber  of  ribs  of  beech  leaves,  and  of  the 
bands  upon  the  capsules  of  poppies,  for  the  shades  of 
color  of  human  eyes,  for  the  nimiber  of  spines  on  the 
backs  of  sJirimps,  and  for  the  number  of  da\^ 
caterpillars  feed  before  they  turn  into  pupae. 

To  summarize  the  foregoing  facts^  we  have  learned 
that  variation  is  univeTsal  throu^out  the  hving  worid, 
and  that  the  primar>'  factors  causing  orcanic  dif- 
ference —  the  coimterparts  of  human  i:  -  in 
the  ca,se  of  dead  mechanisms  —  are  the  in- 
fluences of  the  en\'ironment,  of  organic  physic ..« — 
activity,  and  of  congenital  inheritance.  These  factors 
are  accorded  different  values  in  the  eve '       a  of  new 


122  DOCTRINE  OF  EVOLUTION 

species,  as  we  may  see  more  clearly  at  a  later  juncture, 
but  the  essential  point  here  is  that  they  are  not  un- 
real, although  they  may  not  as  yet  be  described  by 
science  in  final  analytical  terms. 


We  come  now  to  the  second  element  of  the  whole 
process  of  evolution,  namely,  what  we  may  call  over- 
production or  excessive  multiplication.  Like  varia- 
tion and  so  many  other  phenomena  of  nature,  this  is 
so  real  and  natural  that  it  escapes  our  attention  until 
science  places  it  before  us  in  a  new  light.  The  normal 
rate  of  reproduction  in  all  species  of  animals  is  such 
that  if  it  were  unchecked,  any  kind  of  organism  would 
cumber  the  earth  or  fill  the  sea  in  a  relatively  short 
time.  That  this  is  universally  true  is  apparent  from 
any  illustration  that  might  be  selected.  Let  us  take 
the  case  of  a  plant  that  fives  for  a  single  year,  and  that 
produces  two  seeds  before  it  withers  and  dies;  let  us 
suppose  that  each  of  these  seeds  produces  an  adult 
plant  which  in  its  turn  lives  one  year  and  forms  two 
seeds.  If  this  process  should  continue  without  any 
interference,  the  twentieth  generation  after  as  many 
years  would  consist  of  more  than  one  mifiion  descen- 
dants of  the  original  two-seeded  annual  plant,  pro- 
vided only  that  each  individual  of  the  in'  evening 
years  should  live  a  normal  life  and  should  multiply 
at  the  natural  rate.  But  such  a  result  as  this  is  rendered 
impossible  by  the  very  nature  which  makes  annual 
plants  multiply  in  the  way  they  do.  Let  us  take  the 
case  of  a  pair  of  birds  which  produce  four  young  in 
each  of  four  seasons.     Few  would  be  prepared  for  the 


EVOLUTION   AS  A  NATURAL   PROCKSS  123 

figures  enumerating  the  offsi^ring  of  a  single  pair  of 
birds  at  the  end  of  fifteen  years,  if  again  all  individuals 
Uved  complete  and  normal  lives:  at  \\h>  end  uf  the 
time  specified  there  would  be  more  than  two  thousand 
millions  of  descendants.  The  English  sparrow  has  b^en 
on  this  continent  little  more  than  fifty  years;  it  has 
found  the  conditions  in  this  country  favorable  be- 
cause few  natural  enemies  like  those  of  its  original  home 
have  been  met,  and  as  a  consequence  it  ha.s  multi- 
plied at  an  astounding  rate  so  as  to  invade  nearly  all 
parts  of  North  America,  driving  out  many  species 
of  song  birds  before  it.  About  twenty  years  ago 
David  Starr  Jordan  wrote  that  if  the  English  ^i)arr()W 
continued  to  multiply  at  the  natural  rate  of  that  time, 
in  twenty  years  more  there  would  be  one  sparrow  to 
every  square  inch  of  the  state  of  Indiana  ;  but  of  course 
nature  has  seen  to  it  that  this  result  has  not  come 
about.  A  single  conger-eel  may  produce  fifteen  million 
eggs  in  a  single  season,  and  if  this  natural  rate  of 
increase  w^ere  unchecked,  the  ocean  would  be  filled 
solid  with  conger-eels  in  a  few  years.  Sometimes  a 
single  tapeworm,  parasitic  in  the  human  body,  will 
produce  three  hundred  million  embryos;  the  fact 
that  this  animal  is  relatively  rare  diverts  our  attention 
from  the  alarming  fertility  of  the  species  and  the  ex- 
cessive rate  of  its  natural  increase.  Perhaps  the  most 
amazing  figures  are  those  establisluMl  by  the  students 
of  bacteria  and  other  micro-organisms.  Many  kinds 
of  these  primitive  creatures  are  known  when^  the 
descendants  of  a  single  individual  will  luimber  sixt(vii 
to  seventeen  millions  after  twenty-four  hours  of  develop- 
ment under  ordinarilv  favorable  contlitions.     Though 


124  DOCTRINE  OF  EVOLUTION 

a  single  rodlike  individual  taken  as  a  starting-point 
may  be  less  than  one  five-thousandth  of  an  inch  in 
length,  under  natural  circumstances  it  multiplies  at  a 
rate  which  within  five  days  would  cause  its  descendants 
to  fill  all  the  oceans  to  the  depth  of  one  mile.  This  is  a 
fact,  not  a  conjecture ;  the  size  of  one  organism  is 
known,  and  the  rate  of  its  natural  increase  is  known, 
so  that  it  is  merely  a  matter  of  simple  arithmetic  to 
find  out  what  the  result  would  be  in  a  given  time. 

Even  in  the  case  of  those  animals  that  reproduce  more 
slowly,  an  overcrowding  of  the  earth  would  follow  in 
a  very  short  time.  Darwin  wrote  that  even  the  slow- 
breeding  human  species  had  doubled  in  the  preced- 
ing quarter  century.  An  elephant  normally  lives  to 
the  age  of  one  hundred  years ;  it  begins  to  breed  at  the 
age  of  thirty,  and  usually  produces  six  young  by  the 
time  it  is  ninety.  Beginning  with  a  single  pair  of 
elephants  and  assuming  that  each  individual  born 
should  live  a  complete  life,  only  eight  hundred  years 
would  be  requisite  to  produce  nineteen  million  elephants ; 
a  century  or  two  more  and  there  would  be  no  standing 
room  for  the  latest  generation  of  elephants.  It  is  only 
too  obvious  that  such  a  result  is  not  realized  in  nature, 
but  it  is  on  account  of  other  natural  checks,  and  not 
because  the  natural  rate  of  reproductive  increase  is 
anything  but  excessive. 


The  third  element  of  the  process  of  natural  selection 
is  the  struggle  for  existence  which  is  to  a  large  extent 
the  direct  consequence  of  over-multiplication.  Be- 
cause nature  brings  more  individuals    into    existence 


EVOLUTION   AS  A  NATURAL   PROCESS         125 

than  it  can  support,  every  animal  is  involved  in  many- 
sided  battles  with  countless  foes,  and  the  victory  is 
sometimes  with  one  and  sometimes  with  another  par- 
ticipant in  the  conflict.  A  survivor  turns  from  one 
vanquished  enemy  only  to  find  itself  engapjed  in  mortal 
combat  w^ith  other  attacking  forces.  Wherever  we 
look,  we  find  evidence  of  an  unceasing  struggle  for 
life,  and  an  apparently  peaceful  meadow  or  pond  is 
often  the  scene  of  fierce  battles  and  tragic  death  that 
escape  our  notice  only  because  the  contending  armies 
are  dumb. 

A  community  of  ants,  often  comprising  more  in- 
dividuals than  an  entire  European  state,  depends 
for  its  national  existence  upon  its  ability  to  prevail 
over  other  communities  with  which  it  may  engage  in 
sanguinary  wars  where  the  losses  of  a  single  l)attle 
may  exceed  those  of  Gettysburg.  The  developing 
conger-eels  find  a  host  of  enemies  which  greatly  de- 
plete their  numbers  before  they  can  grow  even  into 
infancy.  An  annual  plant  does  not  produce  a  million 
living  offspring  in  twenty  years  because  seeds  do  not 
always  fall  upon  favorable  soil,  nor  do  they  always 
receive  the  proper  amount  of  sunlight  and  moisture, 
or  escape  the  eye  of  birds  and  other  seed-eating  animals. 
These  three  illustrations  bring  out  the  fact  that  there 
are  three  classes  of  natural  conditions  which  must 
be  met  by  every  living  creature  if  it  is  to  succeed  in 
life.  In  detail,  the  struggle  for  existence  is  intra- 
specific,  involving  some  form  of  competition  or  rivalry 
among  the  members  of  a  single  species;  it  is  inter- 
specific,  as  a  conflict  is  waged  by  every  species  with 
other  kinds  of  hving  things;    and  finally  it  involves 


126  DOCTRINE  OF  EVOLUTION 

an  adjustment  of  life  to  inorganic  environmental  in- 
fluences. While  it  may  seem  unjustifiable  to  speak  of 
heat  and  cold  and  sunlight  as  enemies,  the  direct 
effects  produced  by  these  forces  are  to  be  reckoned 
with  no  less  certainty  than  the  attacks  of  living  foes. 

The  three  divisions  of  the  struggle  for  existence  are 
so  important  not  only  in  purely  scientific  respects, 
but  also  in  connection  with  the  analysis  of  human 
biology,  that  we  may  look  a  little  further  into  their 
details,  taking  them  up  in  the  reverse  order.  Re- 
garding the  environmental  influences,  the  way  that  un- 
favorable surroundings  decimate  the  numbers  of  the 
plants  of  any  one  generation  has  already  been  noted, 
and  it  is  typical  of  the  vital  situation  everywhere. 
English  sparrows  are  killed  by  prolonged  cold  and  snow 
as  surely  as  by  the  hawk.  The  pond  in  which  bacteria 
and  protozoa  are  hving  may  dry  up,  and  these  organisms 
may  be  killed  by  the  billion.  Even  the  human  species 
cannot  be  regarded  as  exempt  from  the  necessity  of 
carrying  on  this  kind  of  natural  strife,  for  scores  and 
hundreds  die  every  year  from  freezing  and  sunstroke 
and  the  thirsts  of  the  desert.  Unknown  thousands 
perish  at  sea  from  storm  and  shipwreck,  while  the 
recorded  casualties  from  earthquakes  and  volcanic 
eruptions  and  tidal  waves  have  numbered  nearly  one 
hundred  and  fifty  thousand  in  the  past  twenty-eight 
years.  The  effects  of  inorganic  influences  upon  all 
forms  of  organic  life  must  not  be  underestimated  in  view 
of  such  facts  as  these. 

In  the  second  place,  the  vital  struggle  includes  the  bat- 
tles of  every  species  with  other  kinds  of  living  things  whose 
interests  are  in  opposition.     The  relations  of  protozoa 


EVOLUTION  AS  A  NATURAL  PROCESS  127 

and  bacteria,  conger-eels  and  other  fish,  Kii^hsli  spar- 
rows and  hawks,  plants  and  herbivorous  animals,  are 
typical  examples  of  the  universal  conllict  in  whicl'i  all 
organisms  are  involved  in  some  way.  Again  it  is  only 
too  evident  that  human  beings  nmst  participate  every 
day  in  some  form  of  warfare  with  other  six'cics.  In 
order  that  food  may  be  provided  for  mankind  tlie  lives 
of  countless  wild  organisms  must  be  sacrificed  in  addi- 
tion to  the  great  numbers  of  domesticated  animals 
reared  by  man  only  that  they  may  be  destroyed.  The 
wolf  and  the  wildcat  and  the  panther  have  disapj)eared 
from  many  of  our  Eastern  states  where  thev  furmerlv 
lived,  while  no  longer  do  vast  herds  of  bison  and  wild 
horses  roam  the  Western  prairies.  Because  one  or 
another  hmiian  interest  was  incompatible  with  the 
welfare  of  these  animals  they  have  been  driven  out  by 
the  stronger  invaders. 

That  the  victory  does  not  always  fall  to  the  human 
contestant  is  tragically  demonstrated  by  the  eflects  of 
the  incessant  assaults  upon  man  made  by  just  onekimi 
of  living  enemy,  —  the  bacillus  of  tuberculosis.  Every 
year  more  than  one  hundred  and  twenty-five  thousand 
people  of  the  United  States  die  because  they  are  unable 
to  withstand  its  persistent  attacks;  five  million 
Americans  now  living  are  doomed  to  death  at  the  hands 
of  these  executioners,  and  the  figures  mu.st  be  mure 
than  doubled  to  cover  the  casualties  on  the  human 
side  in  the  battles  with  the  regiments  of  all  the  epccies 
of  bacteria  causing  disease. 

The  competition  between  and  among  the  individuals 
of  one  and  the  same  species  is  the  third  part  of  the 
struggle  for  existence,  and  it  is  often  unsurpassed  in 


128  DOCTRINE  OF  EVOLUTION 

its  ferocity.  When  two  lion  cubs  of  the  same  Utter 
begin  to  shift  for  themselves,  they  must  naturally  com- 
pete in  the  same  territory,  and  their  contest  is  keener 
than  that  which  involves  either  of  them  and  a  young 
lion  born  ten  or  fifteen  miles  away.  The  seeds  of  one 
parent  plant  falling  in  a  restricted  area  will  be  engaged  in 
a  competitive  struggle  for  existence  that  is  much  more 
intense  than  many  other  parts  of  nature's  warfare. 
In  brief,  the  intensity  of  the  competition  will  be  directly 
proportional  to  the  similarity  of  two  organisms  in 
constitution  and  situation,  and  to  the  consequent 
similarity  of  vital  welfare.  The  interests  of  the  white 
man  and  the  Indian  ran  counter  to  each  other  a  few 
hundred  years  ago,  and  the  more  powerful  colonists 
won.  The  assumption  of  the  white  man's  burden  too 
often  demonstrates  the  natural  effect  of  diversity  of 
interest,  and  the  domination  of  the  stronger  over  the 
weaker.  In  any  civilized  community  the  manufacturer, 
farmer,  financier,  lawyer,  and  doctor  must  struggle 
to  maintain  themselves  under  the  conditions  of  their 
total  inorganic  and  social  environments ;  and  in  so  far 
as  the  object  of  each  is  to  make  a  living  for  himself, 
they  are  competitors.  But  the  contest  becomes  more 
absorbing  when  it  involves  broker  and  broker,  lawyer 
and  lawyer,  financier  and  magnate,  because  in  each 
case  the  contestants  are  striving  for  an  identical  meed 
of  success. 

Although  the  severity  of  the  conflict  imposed  by 
nature  is  somewhat  modified  in  the  case  of  social 
organisms,  where  community  competes  with  com- 
munity and  nation  with  nation,  no  form  of  social 
organization  has  yet  been  developed  where  the  individ- 


.<^A 


EVOLUTION  AS  A  NATURAL  PRQCIiSS         129 

ual  contest  carried  on  by  the  mombers  of  one  coninui- 
nity  has  been  done  away  with.  It  is  an  inexoraljle  law 
of  nature  that  all  hving  things  must  fight  daily  and 
hourly  for  their  very  hves,  because  so  many  are  brought 
into  the  world  with  each  new  generation  that  there  is 
not  sufficient  room  for  all.  No  organism  can  escai)e 
the  struggle  for  existence  except  by  an  uncoiKhlional 
surrender  that  results  in  death.  Everywhere  we  turn 
to  examine  the  happenings  of  organic  life  wo  can  find 
nothing  but  a  wearisome  warfare  in  which  it  is  the 
ultimate  and  cruel  lot  of  every  contestant  to  admit 
defeat. 


lat  now  are  the  results  of  variation,  over-multi- 
plication, and  competition?  Since  some  must  die 
because  nature  cannot  support  all  that  she  jjnxhiccs, 
since  only  a  small  proportion  of  those  that  enter  upon 
life  can  find  a  foothold  or  successfully  meet  the  hordes 
of  their  enemies,  which  will  be  the  ones  to  survive? 
Surely  those  that  have  even  the  shghtest  advantage 
over  their  fellows  will  live  when  their  companions 
perish.  It  is  impossible  that  the  result  could  be  other- 
wise ;  it  must  follow  inevitably  from  what  has  been 
described  before.  The  whole  process  has  its  positive 
and  its  negative  aspects:  the  survival  of  the  fittest 
and  the  elimination  of  the  unfit.  Pcrha]rs  it  would  be 
more  correct  to  say  the  more  real  element  is  the  nega- 
tive one,  for  those  which  are  least  capable  of  meeting 
their  living  foes  and  the  decimating  conditions  of  in- 
organic nature  are  the  first  to  die,  while  the  others 
will  be  able  to  prolong  the  struggle  for  a  longer  or 


130  DOCTRINE   OF  EVOLUTION 

shorter  period  before  they  too  succumb.  Thus  the 
destruction  of  the  unfit  leaves  the  field  to  the  better 
adapted,  that  is,  to  those  that  vary  in  such  a  way  as  to 
be  completely  or  at  least  partially  adapted  to  carry  on 
an  efficient  life.  In  this  way  Darwinism  explains  the 
universal  condition  of  organic  adjustment,  showing 
that  it  exists  because  there  is  no  place  in  nature  for 
the  incompetent. 


Finally  we  come  to  *  the  process  of  inheritance  as 
viewed  by  Darwin,  and  its  part  in  the  production  and 
perfection  of  new  species.  In  every  case,  Darwin  said, 
the  efficiency  or  inefficiency  of  an  animal  depends  upon 
its  characteristics  of  an  inherited  or  congenital  nature. 
Variations  in  these  qualities  provide  the  array  of  more 
or  less  different  individuals  from  which  impersonal 
nature  selects  the  better  by  throwing  out  first  the 
inferior  ones.  An  organism  can  certainly  change  in 
direct  response  to  environmental  influence  or  by  the 
indirect  results  of  use  and  disuse,  but  not  unless  it  is 
so  constituted  by  heredity  as  to  be  able  to  change  adap- 
tively.  Therefore  the  final  basis  of  success  in  life  must 
be  sought  in  the  inherited  constitutions  of  organic  forms. 

For  the  reason  that  the  qualities  which  preserve  an 
animal's  existence  are  already  congenital,  they  are 
already  transmissible,  as  Darwin  contended.  Since 
his  time  much  has  been  learned  about  the  course  of 
inheritance  and  its  physical  basis,  and  the  new  discov- 
eries have  confirmed  the  essential  truth  of  Darwin's 
statement  that  the  congenital  characters  only  possess 
a  real  power  in  the  evolution  of  species. 


EVOLUTION  AS  A  NATURAL   PROCESS  L31 

We  must  devote  some  time  to  the  subject  of  inheri- 
tance at  a  later  juncture,  but  before  leaving  the  matter 
an  additional  point  must  be  estabhshcd  here;  the 
selective  process  deals  inmiediatcly  with  congenital 
results,  as  the  heritable  characters  that  mak('  for  success 
or  failure  in  Hfe,  but  by  doing  this  it  really  selects  the 
group  of  congenital  factors  behind  and  antecedent  to 
their  effects.  For  example,  an  ape  that  survives  be- 
cause of  its  superior  cunning,  does  so  because  it  varies 
congenitally  in  an  improved  direction ;  ^and  the  factors 
that  have  made  it  superior  are  indirectly  but  no  less 
certainly  preserved  through  the  survival  of  their  results 
in  the  way  of  efficiency.  Hereditary  strains  are  thus  the 
ultimate  things  selected  through  the  organic  constitu- 
tions that  they  determine  and  produce. 


Natural  selection,  as  the  whole  of  this  intricate 
process,  is  simply  trial  and  error  on  a  gigantic  scale. 
Nature  is  such  that  thousands  of  varying  individuals 
are  produced  in  order  that  a  mere  handful  or  only 
one  survivor  may  be  chosen  to  bear  the  burden  of  carr}'- 
ing  on  the  species  for  another  generation.  The  eflect 
of  nature's  process  is  judicial,  as  it  were.  \\'e  may 
liken  the  many  and  varied  conditions  of  life  to  ai;  many 
jurymen,  before  which  every  living  thing  must  appear 
for  judgment  as  to  its  fitness  or  lack  of  it.  A  unani- 
mous verdict  of  complete  or  partial  ai)pr()val  must  be 
rendered,  or  an  animal  dies,  for  the  failure  to  meet  a 
single  vital  condition  results  in  sure  destructit)n.  Of 
course,  we  cannot  regard  selection  as  involving  anything 
like  a  primitive  conscious  choice.     If    is  because  we 


132  DOCTRINE  OF  EVOLUTION 

individualize  all  of  the  complex  totality  of  the  world  as 
''Nature"  with  a  capital  N  that  so  many  people  un- 
consciously come  to  think  of  it  as  a  human-like  personal- 
ity. He  who  would  go  further  and  hold  that  all  of 
nature  is  actually  conscious  and  the  dwelling-place 
of  the  supernatural  ultimate,  must  beware  of  the  logical 
results  of  such  a  view.  What  must  we  think  of 
the  ethical  status  of  such  a  conscious  power  who 
causes  countless  millions  of  creatures  to  come  into  the 
world  and  ruthlessly  compels  them  to  battle  with  one 
another  until  a  cruel  and  tragic  death  ends  their 
existence  ? 

But  that  is  a  metaphysical  matter,  with  which  we 
need  not  concern  ourselves  in  this  discussion ;  the  im- 
portant point  is  that  among  the  everyday  happenings  of 
life  are  processes  that  are  quite  competent  to  account 
for  the  condition  of  adaptation  exhibited  by  various 
animal  forms.  These  processes  are  real  and  natural, 
not  imaginative  or  artificial,  and  so  they  will  remain 
even  though  it  will  become  clear  that  much  is  still  to 
be  learned  about  the  causes  of  variation  and  the  course 
of  biological  inheritance.  Darwin  was  the  first  to 
contend  that  natural  selection  is  but  a  part  of  nature's 
method  of  accomplishing  evolution.  As  such  it  is 
content  to  recognize  variations  and  does  not  concern 
itself  with  the  origin  of  modifications;  it  accepts 
the  obvious  fact  that  congenital  variations  are  in- 
herited, although  it  leaves  the  question  as  to  how 
they  are  inherited  for  further  examination.  Because 
the  doctrine  of  natural  selection  does  not  profess  to 
answer  all  the  questions  propounded  by  scientific 
inquisitiveness,  it  must  not  be  supposed  that  it  fails  in 


EVOLUTION  AS  A  NATURAL  PROCKSS         L33 

its  immediate  purpose  of  giving  a  natural  oxi)lanatiuii 
of  how  evolution  may  be  partly  accounted  for. 


Before  proceeding  to  the  post-Danvinian  investiga- 
tions that  have  done  so  much  to  amplify  the  account 
of  natural  evolution,  let  us  consider  the  contnustod 
explanation  given  by  Lamarck  and  his  followers.  As 
we  have  stated  earlier,  Lamarckianism  is  the  namo  given 
to  the  dof>tnnpJji/i.t  rnnH^(if>"^^^^  Other  tiiaiMliosc  dug 

^to_^^iingenital  factor^may  enter  into  t|if>  |n>i-if-'^v  '}( 
a  species/^ahd  may  add  themselves  toth()se_iil  ready 
>gorn[?rrftTJ~?T?rj^ 

^sgecies.  Let  us  take  the  giralTe'  and  its  long  neck 
as  a  concrete  example.  The  great  length  of  this 
part  is  obviously  an  adaptive  character,  enabling  the 
animal  to  browse  upon  the  softer  leafy  slioots  of  shrubs 
and  trees.  Th-'j  vertebral  column  of  the  neck  comj)rises 
just  the  same  number  of  bones  that  are  present  in  the 
short-neckeJ  relatives  of  this  form,  so  that  we  are 
justified  m  accepting  as  a  fact  the  evolution  of  the 
giraffe's  long  neck  by  the  lengthening  of  each  one  of 
originally  shorter  vertebrcT.  The  Lamarckian  exj)lana- 
tion  of  this  fact  would  be  that  the  earliest  forms  in 
the  ancestry  of  the  giraffe  as  such  stretched  their  necks 
as  they  fed,  and  that  this  peculiar  function  with  its 
correlated  structural  modification  became  habitual. 
The  slight  increase  brought  about  by  any  single  in- 
dividual would  be  inherited  and  transmitted  to  the 
giraffes  of  the  next  generation;  in  other  words,  an 
individually  acquired  character  would  be  inherited. 
The   young   giraffes   of    this    next    generation    would 


134  DOCTRINE  OF  EVOLUTION 

then  begin,  not  where  their  parents  did,  but  from  an 
advanced  condition.  Thus,  by  continued  stretching 
of  the  neck  and  by  continued  transmission  of  the 
elongated  condition,  the  great  length  of  this  part  of 
the  body  in  the  modern  giraffe  would  be  attained. 

The  explanation  of  natural  selection  would  be  quite 
different.  The  Darwinian  would  say  that  all  the  young 
giraffes  of  any  one  generation  would  vary  with  respect 
to  the  length  of  the  neck.  Those  with  longer  necks 
would  have  a  slight  advantage  over  their  fellows  in 
the  extended  sphere  of  their  grazing  territory.  Being 
better  nourished  than  the  others,  they  would  be  stronger 
and  so  they  would  be  more  able  to  escape  from  their 
flesh-eating  foes,  like  the  lion.  For  the  reason  that  their 
variation  would  be  congenital  and  therefore  already 
transmissible,  their  offspring  would  vary  about  the  ad- 
vanced condition,  and  further  selection  of  the  longer 
necked  individuals  would  lead  to  the  modern  result. 

The  Lamarckian  explanation  encounters  one  grave 
difficulty  which  is  not  met  by  the  second  ore,  in  so  far 
as  it  demands  some  method  by  which  a  bodily  change 
may  be  introduced  into  the  stream  of  inh-^ritance. 
So  far,  this  difficulty  has  not  been  overcome,  ^nd  the 
present  verdict  of  science  is  that  the  transmission  of 
characters  acquired  as  the  result  of  other  than  congenital 
factors  is  not  proved.  It  would  be  unscientific  to  say 
that  it  cannot  be  proved  in  the  future,  but  there  are  good 
a  priori  grounds  for  disbelief  in  the  principle,  wiile 
furthermore  the  results  of  experiments  that  have  btjen 
undertaken  to  test  its  truth  have  been  entirely  negati^'-e. 
Rats  and  mice  have  had  their  tails  cut  off  to  see  if  this 
mutilation  would  have  its  effect  upon  their  young,  acd 


EVOLUTION   AS   A  NATURAL   PROCl.SS  L;:, 

though  this  has  been  done  for  nioro  than  one  hundml 
successive  generations  the  IcMigth  of  the  tail  lia,s  not 
been  altered.  Quite  unconscious  of  the  scientific  prol)- 
lem,  many  human  races  have  performed  precisely 
similar  experiments  through  centuries  of  time.  In 
some  classes  of  Chinese,  the  feet  of  young  girls  have  been 
bound  in  such  a  way  as  to  produce  a  small,  malformed 
foot,  but  this  has  not  resulted  in  any  hereditary  dimi- 
nution in  the  size  of  the  feet  of  Chinese  fomales. 
Many  other  similar  mutilations  have  been  practised, 
as  for  example,  the  flattening  of  the  sknll  of  some 
North  American  Indians,  but  the  deformity  must  be 
produced  again  with  each  recurring  generation.  One 
after  another,  the  cases  that  were  supposed  to  give 
positive  evidence  have  been  reinvestigated,  with  the 
result  that  has  been  stated  above.  It  would  seem, 
therefore,  that  heredity  and  congenital  modification 
must  play  by  far  the  greater  part  in  the  evolution 
of  species. 


The  doctrine  of  natural  selection  took  form  in  tlie 
mind  of  Darwin  mainly  on  account  of  threc^  potent 
influences;  these  were,  first,  the  geological  doctrine 
of  uniformitarianism  proposed  by  Lyell,  second,  his 
own  observations  of  wild  life  in  many  lands  and  his 
analysis  of  the  breeder's  results  with  domesticated 
animals,  and  third,  the  writings  of  Mnlthus  d(>aling  with 
overpopulation.  As  Darwin  had  read  the  works 
of  Buffon,  Lamarck,  and  Erasmus  Danvin.  his  grand- 
father, who  had  written  a  famous  treatise  imder  the 
title  of  ^^Zoonomia,"  he  was  familiar  with  the  evidences 


136  DOCTRINE  OF  EVOLUTION 

known  in  his  student  days  tending  to  prove  that  organic 
evlution  was  a  real  natural  process.  Lyell's  doctrine 
of  uniform  geological  history  made  an  early  and  deep 
impression  upon  his  mind,  and  it  led  him  to  ask  himself 
whether  the  efficient  causes  of  past  evolution  might 
not  be  revealed  by  an  analysis  of  the  present  workings 
of  nature.  As  naturalist  of  the  ^'Beagle"  during  its 
four  years'  cruise  around  the  world,  Darwin  saw  many 
new  lands  and  observed  varied  circumstances  under 
w^hich  the  organisms  of  the  tropics  and  other  regions 
lived  their  lives.  The  fierce  struggle  for  existence 
waged  by  the  denizens  of  the  jungle  recalled  to  him 
the  views  of  Malthus  regarding  overpopulation  and 
its  results.  These  and  other  influences  led  him  to 
begin  the  remarkable  series  of  note-books,  from  which 
it  is  interesting  indeed  to  learn  how  the  doctrine  of 
natural  selection  began  to  assume  a  definite  and  per- 
manent form  in  his  mind,  as  year  followed  year,  and 
evidence  was  added  to  evidence.  And  it  is  a  valuable 
lesson  to  the  student  of  science  that  for  twenty-five  years 
Darwin  devoted  all  his  time  to  the  acquisition  of  facts 
before  he  gave  his  doctrine  to  the  world  in  the  famous 
^'Origin  of  Species." 

Darwin  was  particularly  impressed  by  the  way 
mankind  has  dealt  with  the  various  species  of  domesti- 
cated animals,  and  he  was  the  first  naturahst  to 
point  out  the  correspondence  between  the  breeder's 
method  of  ''artificial  selection,"  and  the  world-wide 
process  of  natural  selection.  As  every  one  knows,  the 
breeder  of  race  horses  finds  that  colts  vary  much  in  their 
speed ;  discarding  the  slower  animals,  he  uses  only 
the  swifter  for  breeding  purposes,  and  so  he  perfects 


EVOLUTION  AS  A  NATURAL  PROCKSS         L37 

one  type  of  horse.  With  other  objects  in  view,  the 
heavy  draught  horse,  the  spirited  hackney,  and  the 
agile  polo  pony  have  been  severally  bnni  by  exactly 
the  same  method.  Among  cattle  many  kinds  occur, 
again  the  products  of  an  artificial  or  human  selection; 
hornless  breeds  have  been  originated,  as  well  ius  (jthers 
with  wide-spreading  or  sharply  curved  horns;  the 
Holstein  has  been  bred  for  an  abundant  supply  of 
milk  as  an  object,  while  Jerseys  and  Alderneys  excel 
in  the  rich  quahty  of  their  milk,  ^'arious  kinds  of 
domesticated  sheep  and  rabbits  and  cats  also  owe  their 
existence  to  the  employment  of  the  selfsame  method, 
unconsciously  copied  by  man  from  nature;  f<jr  men 
have  found  variations  arising  naturally  among  their 
domesticated  animals,  and  they  have  simply  substituted 
their  practical  purposes  or  their  fancy  for  nature's 
criterion  of  adaptive  fitness,  preserving  those  that  they 
wish  to  perfect  and  ehminating  those  unfitted  to  their 
requirements  or  ideas. 

In  the  case  of  many  of  these  and  other  examples, 
wild  forms  still  occur  which  seem  to  be  like  the  ancestral 
stock  from  which  the  domesticated  forms  have  been 
produced.  All  the  varied  forms  of  dogs  —  from  ma^fiJ 
to  toy-terrier,  and  from  greyhound  to  dachshund  and 
bulldog  —  find  their  prototypes  in  wild  carnivora  like 
the  wolf  and  jackal.  In  Asia  and  Malaysia  the  junple 
fowl  still  fives,  while  its  domesticated  descendants 
have  altered  under  human  direction  to  become  the 
diverse  strains  of  the  barnyard,  and  even  the  peculiar 
Japanese  product  with  tail  feathers  sometimes  as  long 
as  twenty  feet.  That  far-reaching  changes  can  be 
brought  about  in  a  relatively  short  time  is  pwvcd  by 


138  DOCTRINE  OF  EVOLUTION 

the  history  of  the  game  cock,  which  has  nearly  doubled 
in  height  since  1850,  while  at  the  same  time  its  slender 
legs,  long  spurs,  and  other  qualities  have  been  perfected 
for  the  cruel  sport  for  which  it  has  been  bred.  Again, 
the  wild  rock  pigeon  seems  to  be  the  ancestral  form 
from  which  the  fantail  and  pouter  and  carrier-pigeon 
with  their  diverse  characters  have  taken  their  origin. 

It  is  true  that  some  biologists  have  urged  certain 
technical  objections  to  the  employment  of  domesticated 
animals  and  their  history  as  analogies  to  the  processes 
and  results  in  wild  nature.  To  my  mind,  however, 
artificial  selection  is  truly  a  part  of  the  whole  process 
of  natural  selection.  Man  is  but  one  element  of  the 
environment  of  tame  forms,  and  his  fancy  or  need  is 
therefore  one  of  the  varied  series  of  external  criteria 
that  must  be  met  if  survival  is  to  be  the  result ;  failing 
this,  elimination  follows  as  surely  as  under  the  conditions 
of  an  area  uninhabited  or  uninfluenced  by  mankind. 
Congenital  variation  is  real,  selection  is  real,  and  the 
heredity  of  the  more  fit  modification  is  equally  real. 
Surely  Darwin  was  right  in  contending  that  the  facts 
of  this  class  amplify  the  conception  of  natural  selection 
developed  on  the  basis  of  an  analysis  of  wild  life. 


Knowing  the  elements  of  the  selective  process,  it  is 
possible  to  analyze  and  to  understand  many  significant 
phenomena  of  nature,  and  to  gain  a  clearer  conception  of 
the  results  of  the  struggle  for  existence,  especially  when 
the  human  factor  is  involved.  Let  us  see  how  much 
is  revealed  when  the  foregoing  results  are  employed  in 
a  further  study  of  some  of  nature's  vital  situations. 


EVOLUTION  AS  A  NATURAL   PUOCICSS         UU 

As  a  consequence  of  the  many-sided  stniKgle  for 
existence,  the  interrelations  of  a  series  of  species  will 
approach  a  condition  of  orpiilihriiim  in  an  area  where 
the  natural  circumstances  remain  relatively  undislurlM-.j 
for  a  long  time.  For  examj)le,  anions  the  field-mice  of 
one  generation,  just  as  many  individuals  will  survive  as 
will  be  able  to  find  food  and  to  escape  hereditary  foea 
such  as  cats  and  snakes  and  owls.  The  numhrr  of  owls, 
in  their  turn,  wdll  be  determined  by  the  number  of 
available  mice  and  other  food  organisms,  as  well  us 
by  the  severity  of  the  adverse  circumstances  that  caui^ 
elimination  of  the  less  fit  among  the  fledglings  brouglit 
into  the  world.  The  vital  chain  of  connections  Ls 
sometimes  astonishingly  long  and  intricate.  One  n»- 
markable  illustration  is  given  by  Fiske,  a-s  an  elal)ora- 
tion  of  an  example  cited  by  Darwin.  He  points  out 
that  the  fine  quahty  of  the  traditional  roast  beef  of  Kng- 
land  is  directly  determined  by  the  number  of  elderly 
spinsters  in  that  country.  The  chain  of  circumstances 
is  as  follows  :  the  quahty  of  the  clover  fields,  furnish- 
ing the  best  food  for  cattle,  dei)ends  largely  upon  the 
visits  to  the  clover-blossoms  b}'  wild  bees,  that  accom- 
plish the  fertilization  of  the  flowers  by  carrying  i)ollen 
upon  their  bodies  from  one  plant  to  another.  Field- 
mice  devour  the  young  in  the  nests  of  these  l)ees.  .<o  if 
there  are  few  field-mice  there  will  ])v  many  bees,  and 
consequently  better  grazing  for  the  cattle.  The  number 
of  field-mice  will  vary  according  to  the  abundance 
of  cats,  and  so  the  number  of  these  domestic  animals  will 
exert  an  influence  upon  the  whole  foregoing  rhain  of 
forms.  But,  as  Fiske  points  out,  cats  are  the  favorite 
companions  of  elderly  spinsters;  therefore,  if  there  are 


140  DOCTRINE  OF  EVOLUTION 

many  of  the  latter,  there  will  be  more  cats,  fewer  field- 
mice,  more  bees,  richer  clover  fields,  and  finer  cattle  ! 
Each  link  is  real  and  the  whole  chain  is  a  characteristic 
example  of  the  countless  ways  that  the  natural  destinies 
of  living  things  are  interrelated  and  intertwined. 

The  reality  of  such  organic  interrelationship's  is 
revealed  with  wonderful  clearness  in  the  numerous 
instances  where  some  disturbing  factor  has  altered  one 
or  another  element  of  the  balanced  system.  The 
invasion  of  the  new  world  by  Europeans  has  directly 
led  to  the  partial  or  complete  extinction  of  the  tribes 
of  Indians  to  whom  the  land  formerly  belonged ;  they 
have  disappeared  almost  entirely  from  our  state  of 
New  York,  together  with  the  bear  and  wolf  and  many 
other  species  of  animals  that  formerly  existed  here. 
Wild  horses  and  bison  have  also  vanished  before  the 
advances  of  civilization  and  the  alteration  of  their 
homes.  Sometimes  the  extermination  of  one  pest 
has  resulted  in  an  increase  in  the  number  of  another 
through  human  interference  with  nature's  equilibrium. 
In  some  of  our  Western  states,  a  bounty  was  offered  for 
the  scalps  of  wolves,  so  as  to  lessen  the  number  of  these 
predatory  foes  of  sheep.  But  when  the  wolves  were 
diminished  in  number,  their  wild  food-animals,  the 
prairie  dogs,  found  their  lot  much  bettered,  and  they 
have  multiplied  so  rapidly  that  in  some  places  they 
have  become  even  more  destructive  than  the  wolves. 

One  of  the  most  remarkable  illustrations  is  that  of 
the  rabbits  introduced  into  Australia.  This  island 
continent  was  cut  off  from  the  surrounding  lands  long 
before  the  higher  mammals  evolved  in  far  distant  re- 
gions, so  that  the  balance  of  nature  was  worked  out 


EVOLUTION  AS  A  NATURAL  PROCICSS         141 

without  reference  to  animals  like  the  rabbit.  When 
the  first  of  these  were  introduced  they  found  a  territory 
without  natural  enemies  where  everytliin^^  was  favor- 
able. They  promptly  multiplied  so  raj)idly  that  within 
a  few  years  their  descendants  were  numerous  enough  to 
eat  up  practically  every  green  thing  they  could  reach. 
Two  decades  ago,  the  single  province  of  Queensland  was 
forced  to  expend  $85,000,000  in  a  vain  cfTort  to  put 
down  the  rabbit  plague.  The  remarkable  statement  has 
been  made  that  in  some  places  nature  has  taken  a  hand 
in  causing  a  new  type  of  rabbit  to  evolve.  Finding  the 
situation  desperate,  some  of  the  animals  have  begun 
to  develop  into  tree-climbing  creatures.  The  animals 
exist  in  such  numbers  that  the  available  food  upon  the 
ground  is  insufficient  for  all,  and  so  some  elimination 
results.  But  the  young  rabbits  with  longer  claws, 
varying  in  this  way  on  account  of  congenital  factors, 
have  an  advantage  over  their  fellows  because  tliey 
can  climb  some  of  the  trees  and  so  obtain  food  inac- 
cessible to  the  others.  If  the  facts  are  correctly 
reported,  and  if  the  process  of  selection  on  the  basis 
of  longer  claws  and  the  chmbing  habit  is  continued, 
the  original  type  of  animal  is  splitting  up  into  a  form 
that  will  remain  the  same  and  live  upon  the  ground, 
and  another  that  will  be  to  all  intents  and  inirp(»ses 
a  counterpart  of  our  familiar  stjuirrel.  All  the  evi- 
dence goes  to  show  that  squirrels  have  evolved  from 
terrestrial  rodents;  if  the  data  relating  to  Australian 
rabbits  are  correct,  nature  is  again  i)roducinp  a 
squirrel-like  animal  by  evolution  in  a  region  where 
the  former  natural  situation  has  been  interfered  with 
by  man. 


142  DOCTRINE  OF  EVOLUTION 

The  laws  of  biological  inheritance  have  received 
close  and  deep  study  by  numerous  investigators  of 
Darwinian  and  post-Darwinian  times,  because  from 
the  first  it  was  clearly  recognized  that  a  complete 
description  of  nature's  method  of  accomplishing  evolu- 
tion must  show  how  species  maintain  the  same  general 
characteristics  from  generation  to  generation,  and  also 
how  new  qualities  may  be  fixed  in  heredity  as  species 
transform  in  the  course  of  time.  Before  our  modern 
era  in  biology,  the  fact  of  inheritance  was  accepted  as 
self-sufficient ;  now  much  is  known  that  supplements 
and  extends  the  incomplete  account  given  by  natural 
selection  of  the  way  evolution  takes  place. 

It  is  not  possible  in  the  present  brief  outline  to  de- 
scribe all  the  results  of  recent  investigations,  but  some 
of  them  are  too  important  to  be  passed  over.  Perhaps 
the  most  interesting  one  is  that  the  laws  of  heredity 
seem  to  be  the  same  for  man  and  other  kinds  of  living 
creatures,  as  proved  by  Galton  and  Pearson  and  many 
'others  w^ho  have  dealt  with  such  characters  as  human 
stature,  human  eye  color,  and  an  extensive  series  of 
the  peculiarities  of  lower  animals  and  even  of  plants. 

The  researches  dealing  with  the  physical  basis  of  in- 
heritance and  its  location  in  the  organism  have  yielded 
the  most  striking  and  brilliant  results.  Darwin  him- 
self realized  that  the  doctrine  of  natural  selection  was 
incomplete,  as  it  accepted  at  its  face  value  the  inherit- 
ance of  congenital  racial  qualities  without  attempting 
to  describe  the  way  an  egg  or  any  other  germ  bears 
them,  and  he  endeavored  to  round  out  his  doctrine  of 
selection  by  adding  the  theory  of  pangenesis.  Accord- 
ing to  this,  every  cell  of  every  tissue  and  organ  of  the 


EVOLUTION   AS  A  NATURAL   PROCESS         M3 

body  produces  minute  particles  called  Remmules,  which 
partake  of  the  characters  of  the  cells  thai  jiroduce 
them.  The  gemmules  were  supposed  to  he  traiisi)orted 
throughout  the  entire  body,  and  to  cungregate  in  the 
germ-cells,  which  in  a  sense  would  be  minute  editions 
of  the  body  which  bears  them,  and  would  then  be 
capable  of  producing  the  same  kind  of  a  body.  If 
true,  this  view  would  lead  to  the  acceptance  of 
Lamarck's  or  even  Buffon's  doctrine,  for  changes  in- 
duced in  any  organ  by  other  than  congenital  factors 
could  be  impressed  upon  the  germ-cell,  and  would 
then  be  transported  together  with  the  original  specific 
characters  to  future  generations.  Darwin  wa,s  indeed 
a  good  Lamarckian. 

But  the  researches  of  post-Darwinians,  and  especially 
those  of  the  students  of  cellular  phenomena,  have  dem- 
onstrated that  such  a  view  has  no  real  basis  in  fact. 
Many  naturalists,  like  Naegeli  and  A\'iesner,  were 
convinced  that  there  was  a  specific  substance  concerned 
with  hereditary  qualities  as  in  a  larger  way  protoplasm 
is  the  physical  basis  of  life.  It  remained  for  Weismann 
to  identify  this  theoretical  substance  with  a  specific 
part  of  the  cell,  namely,  the  deepl}'  staining  sui)stance, 
or  chromatin,  contained  in  the  nucleus  of  every  cell. 
Bringing  together  the  accumulating  observations  of 
the  numerous  cytologists  of  his  time,  and  utilizing  them 
for  the  development  of  his  somewhat  speculative  theo- 
ries, Weismann  pubhshed  in  1SS2  a  volume  calh^l  "The 
Germ  Plasm,"  w^hich  is  an  innnortal  foundation  for 
all  later  work  on  inheritance.  The  essential  j)rin(Mples 
of  the  germ-plasm  theory  are  somewhat  as  follows. 
The  chromatin  of  the  nucleus  contains  the  determinanta 


144  DOCTRINE   OF  EVOLUTION 

of  hereditary  qualities.  In  reproduction,  the  male 
sex-cell,  which  is  scarcely  more  than  a  minute  mass  of 
chromatin  provided  with  a  thin  coat  of  protoplasm  and 
a  motile  organ,  fuses  with  the  egg,  and  the  nuclei  of 
the  two  cells  unite  to  form  a  double  body,  which  con- 
tains equal  contributions  of  chromatin  from  the  two 
parental  organisms.  This  gives  the  physical  basis 
for  paternal  inheritance  as  well  as  for  maternal  inheri- 
tance, and  it  shows  why  they  may  be  of  the  same  or 
equivalent  degree.  'V\Tien,  now,  the  egg  divides,  at 
the  first  and  later  cleavages,  the  chromatin  masses  or 
chromosomes  contained  in  the  double  nucleus  are  split 
lengthwise  and  the  twin  portions  separate  to  go  into 
the  nuclei  of  the  daughter-cells.  As  the  same  process 
seems  to  hold  for  all  the  later  divisions  of  the  cleavage- 
cells  whose  products  are  destined  to  be  the  various 
tissue  elements  of  the  adult  body,  it  follows  that  all 
tissue-cells  would  contain  chromatin  determinants 
derived  equally  from  the  male  and  female  parents. 
As  of  course  only  the  germ-cells  of  an  adult  organism 
pass  on  to  form  later  generations,  and  as  their  content 
of  chromatin  is  derived  not  from  the  sister  organs 
of  the  body,  but  from  the  original  fertilized  egg,  there  is 
a  direct  stream  of  the  germ  plasm  which  flows  contin- 
uously from  the  germ-cell  to  germ-cell  through  succeed- 
ing generations.  It  would  seem,  therefore,  that  the 
various  organic  systems  are,  so  to  speak,  sister  products 
in  embryonic  origin.  The  reproductive  organs  are  not 
produced  by  the  other  parts  of  the  body,  but  their  cells 
are  the  direct  descendants  of  the  common  starting- 
point  ,  namely,  the  egg.  As  the  cells  of  the  reproductive 
organs  are  the  only  ones  that  pass  over  and  into  the 


EVOLUTION  AS  A  NATURAL  PROCESS    145 

next  and  later  generations,  it  will  be  evident,  in  the 
first  place,  that  the  germ  plasm  of  their  nuclei  is  the 
only  essential  substance  that  connects  parent  and  off- 
spring. This  stream  of  germ  plasm  passes  on  in  direct 
continuity  through  successive  generations  —  from  egg 
to  the  complete  adult,  including  its  own  germ-cells, 
through  these  to  the  next  adult,  with  its  germ-cells, 
and  so  on  and  on  as  long  as  the  species  exists.  It  does 
not  flow  circuitously  from  egg  to  adult  and  then  to  new 
germ-cells,  but  it  is  direct  and  continuous,  and  appar- 
ently it  cannot  pick  up  any  of  the  body-changes  of  an 
acquired  nature.  Now  we  see  why  individual  accjuisi- 
tions  are  not  transmitted.  The  hereditary  stream  of 
germ  plasm  is  already  constituted  before  an  animal 
uses  its  parts  in  adult  life ;  we  cannot  see  how  altera- 
tions in  the  structure  of  mature  body  parts  through  use 
and  adjustment  to  the  environment  can  be  introduced 
into  it  to  become  new  qualities  of  the  species. 

It  must  be  clear,  I  am  sure,  that  this  theory  supple- 
ments natural  selection,  for  it  describes  the  physical 
basis  of  inheritance,  it  demonstrates  the  efficiency  of 
congenital  or  germ-plasmal  factors  of  variation  in  con- 
trast with  the  Lamarckian  factors,  and  finally  in  the 
way  that  in  the  view  of  Weismann  it  accounts  for  tlie 
origin  of  variations  as  the  result  of  the  commingling 
of  two  differing  parental  streams  of  germ  plasm. 

At  first,  for  many  reasons,  Weismann's  theories  did 
not  meet  with  general  acceptance,  but  during  recent 
years  there  has  been  a  marked  return  to  many  of  his 
positions,  mainly  as  the  result  of  further  cytological 
discoveries,  and  of  the  formulation  of  Mendel's  Law  and 
of  De  Vries's  mutation  theory.     The  first-named  law 


146  DOCTRINE  OF  EVOLUTION 

was  propounded  by  Gregor  Mendel  on  the  basis  of 
extensive  experiments  upon  plants  conducted  during 
many  years,  1860  and  later,  in  the  obscurity  of  his 
monastery  garden  at  Altbriinn,  in  Austria.  It  was 
rescued  from  oblivion  by  De  Vries,  who  found  it  buried 
in  a  mass  of  literature  and  brought  it  to  light  when  he 
published  his  renowned  Mutation  Theory  in  1901. 
Mendelian  phenomena  of  inheritance,  confirmed  and 
extended  by  numerous  workers  with  plants  and  ani- 
mals, prove  that  in  many  cases  portions  of  the  streams 
of  germ  plasm  that  combine  to  form  the  hereditary 
content  of  organisms  may  retain  their  individuality 
during  embryonic  and  later  development,  and  that  they 
may  emerge  in  their  original  purity  when  the  germ-cells 
destined  to  form  a  later  generation  undergo  the  pre- 
paratory processes  of  maturation.  They  demonstrate 
also  the  apparent  chance  nature  of  the  phenomena  of 
inheritance.  To  my  mind  the  most  striking  and  sig- 
nificant result  in  this  field  is  the  demonstration  that  a 
particular  chromosome  or  chromatin  mass  determines 
a  particular  character  of  an  adult  organism,  which  is 
quite  a  different  matter  from  the  reference  of  all  the 
hereditary  characters  to  the  chromatin  as  a  whole. 
Wilson  and  others  have  brought  forward  convincing 
proof  that  the  complex  character  of  sex  in  insects 
actually  resides  in  or  is  determined  by  particular  and 
definite  masses  of  this  wonderful  physical  basis  of 
inheritance. 

Mendel's  principles  also  account  in  the  most  remark- 
able way  for  many  previously  obscure  phenomena, 
like  reversion,  or  a  case  where  a  child  resembles  its 
grandparent  more  than  it  does  either  of  its  parents; 


EVOLUTION  AS  A  NATURAL  PROCESS         147 

such  phenomena  are  due,  so  to  speak,  to  the  rise  to 
the  surface  of  a  hidden  stream  of  germ  plasm  that  had 
flowed  for  one  or  many  generations  beneath  its  accom- 
panying currents.  I  beheve  that  the  law  is  replacing 
more  and  more  the  laws  of  Galton  and  Pearson,  formu- 
lated as  statistical  summaries  of  certain  phenomena 
of  human  inheritance  taken  en  masse.  According  to 
Galton's  celebrated  law  of  ancestral  inheritance,  the 
qualities  of  any  organism  are  determined  to  the  ex- 
tent of  a  certain  fraction  by  its  two  parents  taken 
together  as  a  ''mid-parent,"  that  a  smaller  defi- 
nite fraction  is  contributed  by  the  grandparents  taken 
together  as  a  mid-grandparent,  and  so  on  to  earlier 
generations.  But  Mendel's  Law  has  far  greater  defi- 
niteness,  it  explains  more  accurately  the  cases  of 
alternative  inheritance,  and  it  may  be  shown  to  hold 
for  blended  and  mosaic  inheritance  as  well. 

De  Vries's  new  ''mutation  theory"  is  clearly  not  an 
alternative  but  a  complementary  theory  to  natural 
selection,  the  Weismannian  and  Mendelian  theories. 
Like  these  last,  it  emphasizes  the  importance  of  the 
congenital  hereditary  quahties  contained  in  the  germ 
plasm,  though  unlike  the  Darwinian  doctrine  it  shows 
that  sometimes  new  forms  may  arise  by  sudden  leaps 
and  not  necessarily  by  the  slow  and  gradual  accumula- 
tion of  slight  modifications  or  fluctuations.  The 
mutants  like  any  other  variants  must  present  them- 
selves before  the  jury  of  environmental  circumstances, 
which  passes  judgment  upon  their  condition  of  adapta- 
tion, and  they,  too,  must  abide  by  the  verdict  that 
means  life  or  death. 

From  what  has  been  said  of  these  post-Darwinian 


148  DOCTRINE  OF  EVOLUTION 

discoveries,  the  Lamarckian  doctrine,  which  teaches 
that  acquired  non-congenital  characters  are  trans- 
mitted, seems  to  be  ruled  out.  I  would  not  lead  you 
to  believe  that  the  matter  is  settled.  I  would  say  only 
that  the  non-transmission  of  racial  mutilations,  nega- 
tive breeding  experiments  upon  multilated  rats  and 
mice,  the  results  of  further  study  of  supposedly  trans- 
mitted immunity  to  poisons  —  that  all  these  have  led 
zoologists  to  render  the  verdict  of  ^4iot  proved."  The 
future  may  bring  to  light  positive  evidence,  and  cases 
like  Brown-Sequard's  guinea-pigs,  and  results  like 
those  of  MacDougal  with  plants,  and  of  Tower  with 
beetles,  may  lead  us  to  alter  the  opinion  stated.  But 
as  it  stands  now  most  investigators  hold  that  there 
are  strong  general  grounds  for  disbelief  in  the  principle, 
and  also  that  it  lacks  experimental  proof. 


The  explanation  of  natural  evolution  given  by  Dar- 
winism and  the  principles  of  Weismann,  Mendel,  and 
De  Vries,  still  fails  to  solve  the  mystery  completely, 
and  appeal  has  been  made  to  other  agencies,  even 
to  teleology  and  to  ^'unknown"  and  ^^ unknowable'' 
causes  as  well  as  to  circumstantial  factors.  A  com- 
bination of  Lamarckian  and  Darwinian  factors  has 
been  proposed  by  Osborn,  Baldwin,  and  Lloyd  Morgan, 
in  the  theory  of  organic  selection.  The  theory  of 
orthogenesis  propounded  by  Naegeli  and  Eimer,  now 
gaining  much  ground,  holds  that  evolution  takes  place 
in  direct  lines  of  progressive  modification,  and  is  not 
the  result  of  apparent  chance.  Of  these  and  similar 
theories,  all  we  can  say  is  that  if  they  are  true,  they  are 

PROPERTY  UBRART 

N.  C.  State  College 


EVOLUTION  AS  A  NATURAL  PROCESS    149 

not  so  well  substantiated  as  the  ones  we  have  reviewed 
at  greater  length. 

The  task  of  experimental  zoology  is  to  work  more 
extensively  and  deeply  upon  inheritance  and  variation, 
combining  the  methods  and  results  of  cellular  biology, 
biometrics,  and  experimental  breeding.  We  may  safely 
predict  that  great  advances  will  be  made  during  the 
next  few  years  in  analyzing  the  method  of  evolution  ; 
and  that  a  few  decades  hence  men  will  look  back  to 
the  present  time  as  a  period  of  transition  like  the 
era  of  reawakened  interest  and  renewed  investigation 
that  followed  the  appearance  of  the  ''Origin  of  Species." 
For  the  present,  we  can  justly  say  that  evolution,  so 
far  as  it  is  understood,  is  a  real  and  natural  process. 


THE     PHYSICAL     EVOLUTION     OF     THE     HUMAN     SPECIES 

AND   OF   HUMAN   EACES 

The  teachings  of  science  that  relate  to  the  origin  and 
history  of  the  human  species  constitute  for  us  the  most 
important  part  of  the  whole  doctrine  of  organic  evolu- 
tion ;  and  now,  having  completely  outlined  this  doc- 
trine as  a  general  one,  we  are  brought  to  the  point 
where  we  must  deal  frankly  and  squarely  with  the 
insistent  questions  arising  on  all  sides  as  to  the  way 
that  mankind  is  involved  in  the  vast  mechanism  of 
nature's  order.  These  questions  have  been  ignored 
heretofore,  in  order  that  the  natural  history  of  animals 
in  general  might  be  discussed  without  any  interference 
on  the  part  of  purely  human  interest  and  concern.  It 
now  becomes  our  privilege,  and  our  duty  as  well,  to 
employ  and  apply  the  principles  we  have  learned  in 
order  to  understand  more  completely  the  origin  of  the 
human  body  as  an  organic  type,  the  history  of  human 
races,  the  development  of  human  faculty  and  of  social 
institutions,  and  the  evolution  finally  of  even  the  high- 
est elements  of  human  life.  These  are  scientific  prob- 
lems, and  if  we  are  to  solve  them  we  must  employ 
the  now  familiar  methods  of  science  which  only  yield 
sure  results. 

We  must  not  underestimate  the  many  difficulties 
to  be  encountered,  for  the  field  before  us  is  a  vast 

150 


EVOLUTION  OF  THE  HUMAN  SPECIES         151 

territory  of  complex  human  life  and  of  manifold  human 
relations.  Without  prolonged  exercise  in  scientific 
methods,  it  is  impossible  to  view  our  own  kind  imper- 
sonally, as  we  do  the  creatures  of  lower  nature.  Further- 
more it  seems  to  many  that  an  analysis  of  human  life 
and  biological  history,  even  if  it  is  possible,  must  alter 
or  degrade  mankind  in  some  degree ;  this  is  no  more 
true  than  that  a  knowledge  of  the  principles  of  engineer- 
ing according  to  which  the  Brooklyn  Bridge  has  been 
constructed  renders  that  structure  any  different  or 
unsafe  for  travel.  Man  remains  man,  whether  we  are 
in  utter  ignorance  of  his  mode  of  origin,  or  whether  we 
know  all  about  his  ancestry  and  about  the  factors  that 
have  made  him  human.  It  is  because  our  species 
appears  to  occupy  a  superior  and  isolated  position  above 
the  rest  of  nature  that  the  mind  seems  reluctant  to 
follow  the  guidance  of  science  when  it  conducts  its 
investigations  into  the  history  of  seemingly  privileged 
human  nature.  And  it  is  feared  also,  that  if  evolution 
is  proven  for  man  as  well  as  for  all  other  kinds  of  ani- 
mals, our  cherished  ideas  and  our  outlook  upon  many 
departments  of  human  hfe  must  be  profoundly  affected. 
This  may  be  so,  but  science  endeavors  only  to  find  out 
the  truth ;  it  cannot  alter  truth,  nor  does  it  seek  to  do 
so.  We  might  well  wish  that  the  world  were  different 
in  many  respects  and  that  we  were  free  from  the  control 
of  many  natural  laws  besides  that  of  evolution,  but  if 
the  real  is  what  it  is,  then  our  duty  is  plain  hohn'c  us  ; 
as  we  think  more  widely  and  deeply  on  the  basis  of 
ripened  experience,  it  becomes  ever  clearer  that  a  knowl- 
edge of  human  history  gives  the  only  sure  guidance  for 
human  life. 


152  DOCTRINE  OF  EVOLUTION 

To  the  zoologist  it  seems  strange  that  so  many  are 
opposed  to  a  scientific  inquiry  into  the  facts  of  human 
evolution,  and  to  the  conclusions  established  by  such 
an  inquiry,  —  though,  to  be  sure,  this  opposition  is 
directly  proportional  to  ignorance  or  misunderstanding 
of  the  nature  and  purpose  of  scientific  investigation  and 
of  human  evolution.  The  naturalist  comes  to  view 
our  species  as  a  kind  of  animal,  and  as  a  single  one  of 
the  hundreds  of  thousands  of  known  forms  of  life; 
thus  the  question  of  human  origin  is  but  a  small  part 
of  organic  evolution,  which  is  itself  only  an  episode  in 
the  great  sweep  of  cosmic  evolution,  endless  in  past 
time  and  in  the  future.  Were  we  some  other  order  of 
beings,  and  not  men,  human  evolution  would  appear  to 
us  in  its  proper  scientific  proportions,  namely,  as  a 
minute  fraction  of  the  whole  progress  of  the  world. 

While  the  foregoing  statements  are  true,  it  is  never- 
theless right  that  a  close  study  should  be  made  of  the 
particular  case  of  mankind.  No  doubt  much  of  the 
naturalist's  interest  in  nature  at  large  is  due  to  his 
conviction  that  the  laws  revealed  by  the  organisms  of  a 
lower  sphere  must  hold  true  for  man,  and  may  explain 
many  things  that  cannot  be  so  clearly  discerned  when 
only  the  highest  type  is  the  subject  of  investigation. 
It  is  only  too  evident  that  little  more  than  a  general 
outline  can  be  given  of  the  wide  subject  or  group  of 
subjects  included  under  the  head  of  human  evolution. 
We  must  divide  the  subject  logically  into  parts,  so  that 
each  one  may  be  taken  up  without  being  complicated 
by  questions  relating  to  topics  of  another  category, 
although  the  findings  in  any  one  department  must 
surely  be  of  importance  for  comparison  with  the  results 


EVOLUTION  OF  THE  HUMAN  SPECIES  153 

established  in  another  section ;  for  if  evolution  is  uni- 
versally true,  the  main  conclusion  in  any  case  must 
assist  the  investigation  of  another,  just  as  comparative 
anatomy  and  embryology  supplement  and  corroborate 
each  other  in  the  larger  survey  of  organic  evolution.  As 
before,  the  illustrations  of  each  department  of  the  subject 
must  be  selected  from  the  stock  of  everyday  observation 
and  information  that  we  already  possess,  for  we  gain 
much  when  we  realize  that  evolution  includes  all  the 
happenings  of  everyday  life  and  thought,  as  well  as  the 
occurrences  of  the  remote  past. 

For  the  present,  then,  the  questions  relating  to  the 
higher  aspects  of  human  life  must  be  put  aside,  only 
that  they  may  be  taken  up  at  the  last.  Social  evolu- 
tion likewise  finds  its  place  in  a  later  section,  after  the 
phenomena  of  mind  and  mental  evolution  receive  due 
attention  and  description.  At  the  present  juncture, 
the  human  species  presents  itself  as  a  subject  for  organic 
analysis  and  classification,  merely  as  a  physical  organ- 
ism. Just  as  the  study  of  locomotives  must  begin  with 
the  detailed  structure  of  machines  in  the  workshop 
before  they  can  be  profitably  understood  as  working 
mechanisms,  so  the  physical  evolution  of  mankind  must 
first  be  made  intelligible  before  it  is  possible  to  prosecute 
successfully  the  studies  dealing  with  the  psychology, 
social  relations,  and  higher  conceptions  that  seem  at 
first  to  be  the  exclusive  properties  of  our  species. 

The  problems  of  physical  evolution  of  man  and  of 
men  fall  into  two  groups.  Those  of  the  first  deal  with 
the  origin  of  the  human  species  as  a  unit,  and  its  com- 
parative relation  to  lower  organisms,  while  those  of 
the  second  part  are  concerned  with  the  further  evolu- 


154        DOCTRINE  OF  EVOLUTION 

tion  of  human  races  that  have  come  to  be  different  in 
certain  details  of  structure  since  the  human  type  as 
such  arose.  In  the  first  part,  all  men  will  be  assumed 
to  be  alike  and  the  members  of  a  homogeneous  species 
whose  fundamental  attributes  are  to  be  compared  with 
those  of  other  animals ;  only  afterwards  will  attention 
be  directed  to  the  differences,  previously  ignored,  that 
divide  human  beings  into  well-marked  varieties.  It 
must  be  evident  even  at  this  point  that  the  mode  of 
evolution  demonstrated  by  the  first  investigation  will 
be  likely  to  bear  some  close  relation  to  the  methods 
by  which  human  races  have  evolved  to  their  present 
diverse  anatomical  situations. 


The  foregoing  classification  of  the  problems  concerned 
with  the  nature  and  origin  of  the  human  species  renders 
it  possible  to  restrict  the  immediate  inquiry  to  a  definite 
and  precise  question.  It  is  this :  does  the  evidence 
relating  to  the  physical  characteristics  of  our  species 
prove  that  man  is  the  product  of  a  supernatural  act  of 
creation,  or  does  it  show  that  man's  place  in  nature  has 
been  reached  by  a  gradual  process  of  natural  evolution  ? 
In  order  to  obtain  an  equally  precise  and  definite 
answer  to  this  question,  referring  to  the  particular  case 
of  most  concern  to  us,  it  is  obvious  that  the  method  to 
be  employed  is  the  one  which  has  given  us  an  under- 
standing of  organic  evolution  as  an  all-inclusive  natural 
process.  The  data  must  be  verified,  related,  and  classi- 
fied, so  that  their  meaning  may  be  concisely  stated  in 
the  form  of  scientific  principles.  What  are  the  facts 
of    human    structure,    comparatively    treated?    How 


EVOLUTION  OF  THE  HUMAN  SPECIES  155 

does  the  human  body  develop?  Does  palaeontology 
throw  any  light  on  the  antiquity  of  man?  Do  the 
rules  of  nature's  order  control  the  lives  of  men  ?  Our 
course  is  now  clear ;  we  shall  take  up  serially  the 
anatomy,  embryology,  and  fossil  history  of  the  human 
species,  in  order  to  see  that  there  is  ample  proof  of  the 
actual  occurrence  of  evolution,  and  then,  as  before, 
we  may  look  about  for  the  causes  which  have  ])roduced 
this  result  by  natural  methods. 

While  it  is  necessary  to  treat  the  subject  directly, 
namely,  by  examining  the  actual  evidences  relating 
to  the  particular  case  in  question,  it  is  worth  while  before 
doing  so  to  point  out  that,  as  the  whole  includes  a  part, 
human  evolution  has  already  been  proved  beyond 
question.  This  conclusion  must  be  accepted,  unless 
reasons  can  be  given  for  excluding  mankind  from  the 
rest  of  the  living  world  as  an  absolutely  unique  type, 
supreme  and  isolated  because  of  some  peculiar  endow- 
ments not  shared  with  the  rest  of  animate  nature.  If 
these  reasons  are  lacking,  and  the  unity  of  organic 
nature  be  recognized,  human  evolution  cannot  be  denied 
unless  some  interpretation  more  reasonable  and  logical 
than  evolution  can  be  given  for  the  whole  mass  of  facts 
exemplified  and  discussed  in  the  foregoing  chajiters. 
We  may  accordingly  approach  the  main  questions  by 
asking  if  there  are  any  reasons  for  regarding  the  human 
species  as  a  unique  and  isolated  type  of  organism. 

At  the  outset,  we  must  recognize  that  in  so  far  as 
the  human  body  is  material,  its  movements  and  mass 
relations  are  controlled  by  physical  principles,  like  all 
other  masses  of  matter.  It  is  well,  indeetl,  that  this  is  so, 
for  if  gravitation  and  the  laws  of  inertia  were  not  con- 


156  DOCTRINE  OF  EVOLUTION 

sistent  and  reliable  principles  holding  true  at  all  times 
and  not  intermittently,  it  would  be  difficult  to  order  our 
lives  with  confidence.  In  the  next  place,  the  general 
principles  of  biology  hold  true  for  the  structure  and 
physiology  of  the  human  species  as  they  do  for  all  other 
living  things.  A  human  body  is  composed  of  eight 
systems  of  organs,  whose  functions  are  identical  with 
the  eight  vital  tasks  of  every  other  animal.  All  these 
organs  are  made  up  of  cells  as  ultimate  vital  units, 
and  the  materials  of  which  human  cells  are  composed 
belong  to  the  class  of  substances  called  protoplasm. 
Human  protoplasm,  like  all  other  living  materials, 
must  replenish  itself,  and  respire  and  oxidize  in  obedi- 
ence to  biological  laws  that  have  been  found  to  be  uni- 
form everywhere.  Thus  the  human  organism  is  no 
more  unique  in  fundamental  organic  respects  than  it  is 
apart  from  the  world  of  physical  processes  and  laws. 

How  does  the  matter  stand  when  the  general  struc- 
tural plan  of  a  human  being  is  examined  ?  Is  it  entirely 
different  from  everything  else  ?  It  is  a  fact  of  common 
knowledge  that  the  human  body  is  supported  by  a 
bony  axis,  the  vertebral  column,  to  which  the  skull  is 
articulated  and  to  which  also  the  skeletal  framework  of 
the  limbs  is  attached.  These  characteristics  place  man 
inevitably  among  the  so-called  vertebrata;  he  is  cer- 
tainly not  an  invertebrate,  nor  is  the  basic  structure  of 
his  body  such  that  a  third  group,  outside  the  inverte- 
brata  and  vertebrata,  can  be  made  to  include  only  the 
single  type  —  man. 

Passing  now  to  the  classes  that  make  up  the  group  of 
vertebrates,  we  meet  first  the  lampreys  or  cyclostomes 
without  jaws,  and  the  others  with  jaws,  such  as  the 


EVOLUTION   OF  THE  HUMAN   SPECIES  157 

fishes,  amphibia,  reptiles,  birds,  and  mammals,  each  class 
distinguished  by  certain  definite  characters  in  addition 
to  the  vertebral  column.  The  fishes  have  gills  and 
scales ;  amphibia  of  to-day  are  scaleless,  and  they  are 
provided  with  gills  when  they  are  young  and  lungs  as 
adults  ;  reptiles  have  scales  and  lungs  ;  ijirds  are  warm- 
blooded and  feathered ;  while  mammals  are  warm- 
blooded and  haired.  Is  the  human  species  a  unique 
kind  of  vertebrate,  or  does  it  find  a  place  in  one  of  these 
classes  ?  The  occurrence  of  hair,  of  a  four-chambered 
heart  which  propels  warm  blood,  of  mammary  glands, 
and  of  other  systematic  characters  marks  this  species 
as  a  kind  of  mammal  and  not  as  a  vertebrate  in  a  section 
by  itself. 

The  members  of  the  class  mammalia  differ  much 
among  themselves ;  and  now  that  we  recognize  clearly 
that  man  is  a  mammalian  vertebrate,  the  next  question 
is  whether  an  order  exists  to  which  our  type  must  be 
assigned,  or  whether  we  have  at  last  reached  a  point 
where  it  is  justifiable  to  establish  an  isolated  division 
to  contain  the  human  species  alone.  We  are  familiar 
with  many  representatives  of  different  mammalian 
orders  and  with  the  kind  of  structural  characteristics 
that  serve  as  convenient  distinctions  in  denoting  their 
relationships.  Horses  and  cattle,  sheep,  and  goats  and 
pigs  resemble  one  another  in  many  respects  besides  their 
hoofs,  and  they  form  one  natural  order ;  the  well- 
developed  gnawing  teeth  of  rats  and  rabbits  and 
squirrels  place  these  forms  together  in  the  order  roden- 
tia  ;  the  structures  adapting  their  possessors  for  a  flesh- 
eating  and  predatory  life  unite  the  tribes  of  the  lion, 
wolf,  bear,  and  seal,  in  the  order  carnivora.     Among 


158  DOCTRINE  OF  EVOLUTION 

these  and  other  orders  of  mammaha  is  one  to  which  the 
lemurs,  monkeys,  and  apes  are  assigned,  because  all 
these  forms  agree  in  certain  structural  respects  that 
place  them  apart  from  the  other  mammalia,  in  the  same 
way,  for  example,  that  the  races  of  white  men  may  be 
recognized  as  a  group  distinct  from  the  black  and  red 
races.  But  comparative  studies,  prosecuted  not  only 
by  those  who  have  been  forced  to  adopt  the  evolutionary 
interpretation,  but  also  by  believers  in  special  creation 
like  Linna3us  and  Cuvier  and  other  more  modern  oppo- 
nents of  evolution,  have  shown  that  the  peculiar  qual- 
ities of  this  order  are  shared  by  the  human  species. 
Indeed,  the  name  of  primates  was  given  to  this  section 
by  Linnaeus  himself,  because  the  human  body  found  a 
place  in  the  array  which  begins  at  the  lower  extreme 
with  the  lemurs  and  the  monkeys  and  ends  with  man 
at  the  other  end.  Again  it  is  found  that  no  separate 
order  of  mammals  exists  to  include  only  the  genus 
Homo. 

To  one  unacquainted  with  the  facts  of  vertebrate 
comparative  anatomy,  the  distinguishing  character- 
istics of  the  primates  seem  to  be  trivial  in  nature.  It 
is  surprising  to  find  how  insignificant  are  the  details 
to  which  appeal  must  be  made  in  order  to  draw  a  line 
between  our  own  division  of  mammalia  and  the  others. 
It  is  well  to  review  them  as  they  are  given  in  the  stan- 
dard text-books  of  comparative  anatomy.  Primates 
are  eutheria,  or  true  mammalia  possessing  a  placental 
attachment  of  the  young  within  the  parent.  The  first 
digits,  namely,  the  ^^ great  toe  "  and  the  ''thumb,"  are 
freely  movable  and  opposable  to  the  others,  so  that  the 
limbs  are  prehensile  and  clasping  structures ;   usually 


EVOLUTION  OF  THE  HUMAN  SPECIES         159 

but  not  always  the  animals  of  this  order  are  tree-dwellers 
in  correlation  with  the  grasping  powers  of  the  feet 
and  hands.  The  permanent  teeth  succeed  a  shorter 
series  of  so-called  ''milk  teeth,"  and  they  are  diverse 
in  structure,  being  incisors,  canines,  or  ''  eye  teeth," 
premolars,  and  molars  ;  the  particular  numbers  of  each 
kind  are  almost  invariable  throughout  the  order  and 
markedly  different  from  those  of  other  orders.  The 
number  of  digits  is  always  five,  and  with  few  exceptions 
they  bear  nails  instead  of  claws.  The  clavicles,  or 
''collar  bones,"  are  well  developed  in  correlation  with 
the  prehensile  nature  of  the  fore  limbs ;  a  bony  ring 
surrounds  the  orbit  or  eye  socket.  Finally  there  are 
two  mammary  glands  by  which  the  young  are  suckled. 
It  is  because  any  other  details  of  difference  between 
man  and  other  forms  are  far  less  marked  than  the 
agreements  in  these  respects,  that  the  human  species 
must  be  regarded  as  a  primate  mammalian  vertebrate. 


The  comparative  study  of  the  human  organism  as  a 
structural  type  has  now  been  narrowed  down  to  a  review 
of  the  various  members  of  the  order  of  primates.  It  is 
the  duty  of  science  to  arrange  these  organisms  accord- 
ing to  the  minor  differences  beneath  the  agreements  in 
major  qualities,  and  to  show  how  they  are  related  in  an 
order  of  evolution.  It  will  appear,  when  this  is  done, 
that  the  supreme  place  is  given  to  the  human  species 
on  account  of  four  and  only  four  characteristics ;  these 
are  (1)  an  entirely  erect  posture,  (2)  greater  brain  devel- 
opment, (3)  the  power  of  articulate  speech,  and  (4)  the 
power  of  reason.     As  we  are  treating  the  human  body 


160  DOCTRINE   OF  EVOLUTION 

as  a  subject  for  comparative  structural  study,  the  third 
and  fourth  characters  do  not  concern  us  here ;  but  it  is 
well  to  point  out  that  they  depend  entirely  upon  the 
second,  and  that  they  are  the  functional  concomitants 
of  the  improved  type  of  brain  belonging  to  the  highest 
type.  Two  characters  remain,  and  in  both  cases  it  is 
significant  that  differences  in  degree  only  are  to  be 
found  by  even  the  closest  analysis.  The  human  brain 
is  the  same  kind  of  brain  that  lower  primates  possess ; 
its  structure  is  unique  in  no  general  respect.  And  as 
regards  the  first-mentioned  character,  comparative 
anatomy  shows,  in  the  first  place,  that  this  also  is 
something  differing  only  in  degree,  and  in  the  second 
place,  that  it  is  due  directly  to  the  development  of  the 
brain.  For  these  reasons  a  survey  of  the  various 
members  of  the  order  of  primates  must  deal  largely 
with  the  progressive  elaboration  of  the  brain  and  the 
entailed  effects  of  this  enlargement. 
The  order  of  primates  is  subdivided  as  follows :  — 

Sub-order  1.  PRO  SI  Mil.     Lemurs. 
Sub-order  2.     ANTHROPOIDEA . 

Family  1.  Hapalidce.     The  marmosets. 

Family  2.  Cehidce.     The      American      or      tailed 

monkeys. 
Family  3.  Cercopithecidce.     The  baboons. 
Family  4.  Simiidce.     The  true  apes. 
Family  5.  Hominidce.     The  human  species. 

Each  one  of  these  subdivisions  is  interesting  in  its 
own  way,  either  because  its  members  depart  from  the 
typical  condition  of  the  whole  order  in  some  respects, 
or  because  of  some  character  that  foreshadows  and  leads 


EVOLUTION   OF  THE  HUMAN   SPECIES  161 

to  a  more  developed  element  of  the  animals  placed  in 
the  higher  sections. 

The  lemurs  are  small  animals  very  much  like  squirrels 
in  their  general  form  and  in  their  tree-climbing  habits. 
They  live  now  almost  exclusively  on  the  island  oi 
Madagascar,  but  palaeontology  shows  that  they  were 
more  widely  spread  at  an  earlier  time.  Thoir  teeth 
are  exactly  like  our  own,  except  that  there  is  one  more 
premolar  on  each  side  of  each  jaw.  The  ''fingers" 
and  ''toes"  bear  nails  like  ours,  again  with  an  exception 
in  the  case  of  the  second  digits  of  the  hind  limbs,  which 
bear  claws.  The  details  of  structure  that  set  these 
animals  apart  from  all  the  rest  of  the  primates  are  too 
small  to  deserve  comment  in  the  present  connection. 

Passing  to  the  true  anthropoids,  or  man-like  primates 
and  man  himself,  the  first  forms  encountered  are  the 
little  marmosets,  which  are  like  the  lemurs  in  some 
ways,  but  in  other  respects  they  resemble  the  famiUar 
tailed  monkeys.  They  are  peculiar  in  having  three 
premolars  and  two  molars  on  either  side  of  both  upper 
and  lower  jaws,  and  also  in  the  fact  that  the  "thumb" 
is  not  opposable  to  the  other  fingers,  while  all  the  digits 
except  the  "great  toes"  bear  claws  instead  of  manhke 
nails.  The  proportion  of  brain-case  and  face  does  not 
differ  much  from  that  in  the  lemurs  and  even  lower 
forms  like  cats,  for  the  brain  has  not  increased  greatly 
in  total  mass,  though  the  cerebrum  is  more  convoluted 
than  in  the  lower  forms. 

The  true  monkeys,  or  Cebida?,  are  more  interesting, 
and  at  the  same  time  they  are  much  more  familiar  to 
every  one,  as  they  are  the  commonest  anthropoids  of 
the   menagerie    and    circus.     Their   wonderful    agility 


162  DOCTRINE  OF  EVOLUTION 

and  sureness  in  climbing  about  is  partly  due  to  the  per- 
fect grasping  power  of  the  lower  limb.  To  all  intents 
and  purposes  the  foot  is  a  hand ;  the  first  toe  is  shorter 
than  the  others,  and  its  free  motion  is  unrestricted  as  in 
the  thumb  of  the  hand.  These  animals  usually  possess 
a  long  tail  which  they  can  use  as  a  prehensile  organ, 
curling  it  about  the  branch  of  a  tree  with  hand-like 
ease  and  grasp.  When  they  run  on  all  fours,  they 
plant  the  palms  and  soles  flat  upon  the  ground.  The 
feature  of  primary  importance  in  a  comparative  sense 
is  the  advanced  structure  of  the  skull.  These  anthro- 
poids are  much  more  intelligent  than  the  lower  forms, 
which  is  a  correlate  of  their  larger  and  more  convoluted 
brains.  The  increase  in  the  total  bulk  of  the  brain 
has  wrought  considerable  change,  not  only  in  the  head, 
but  also  in  the  relation  of  head  to  the  trunk.  The 
cranium,  or  brain-case  of  bone,  is  relatively  larger  than 
the  ^^face,"  and  it  bulges  upward  so  as  to  lie  no  longer 
behind  the  latter  as  it  does  in  the  lower  mammalia. 
In  consequence  of  this  cranial  enlargement,  the  face 
and  eyes  are  swung  downward,  as  it  were,  so  that  the 
line  of  vision  is  not  straight  ahead,  but  depressed  below 
the  horizontal.  In  order  to  look  to  the  front  and  to  the 
immediate  foreground  to  which  it  is  progressing  or  to 
where  its  food  or  enemies  may  be,  the  monkey  must 
bend  back  its  head ;  if  it  is  still,  it  finds  greater  ease 
in  the  upright  sitting  posture  which  it  assumes  readily 
and  naturally. 

The  next  division,  called  the  Cercopithecidse,  in- 
cludes the  baboons  of  the  Old  World.  These  animals 
also  run  upon  all  fours,  and  their  feet  are  handlike  as 
before,   but   the  tail  is  much  reduced.     The  general 


EVOLUTION  OF  THE  HUMAN  SPECIES         163 

appearance  of  the  head  is  doghke,  and  the  brain-case 
arches  Uttle  more  than  it  does  in  the  monkeys,  but  the 
face  projects  forward  as  a  long  muzzle,  with  terminal 
nostrils  close  together.  In  some  respects  the  baboons 
stand  somewhat  away  from  the  line  leading  from  the 
lower  to  higher  anthropoids ;  in  other  characters  they 
approach  the  latter,  for  in  the  teeth  especially  they  are 
identical  with  the  apes  and  with  the  human  species. 

The  Simiidae,  or  true  apes,  possess  an  overwhehning 
importance,  far  beyond  that  of  the  baboons  and  mon- 
keys. There  are  only  four  principal  kinds  now  existing, 
namely,  the  gibbon,  orang-outang,  chimpanzee,  and  the 
gorilla,  of  which  the  first  is  much  less  familiar  than  the 
others.  The  known  species  of  gibbons  occur  in  Indo- 
China  and  the  Malay  Peninsula.  The  typical  animal 
stands  about  three  feet  high ;  its  overarching  brain- 
case,  enlarged  in  conformity  with  the  much  greater 
brain  development,  has  pushed  the  eyes  and  face  still 
further  around  underneath,  so  that  if  the  animal  walks 
upon  all  fours  the  eyes  look  almost  straight  into  the 
ground.  Therefore  it  must  bend  back  its  head  at  an 
extremely  uncomfortable  angle  if  it  is  to  remain  upon  all 
four  feet,  but  it  prefers  to  raise  itself  up  into  the  hu- 
man sitting  posture,  or,  when  it  walks,  it  stands  erect 
upon  its  hind  limbs.  Hence  we  who  are  accustomed 
to  think  of  ourselves  as  the  only  erect  animals  must 
revise  our  opinion,  for  we  find  in  the  gibbon  an  organism 
that  is  nearly,  if  not  quite,  as  advanced  in  this  respect 
as  we  are.  One  peculiar  difference  may  be  pointed  out, 
—  the  walking  gibbon  stretches  out  its  great  long  arms 
to  the  sides  in  order  to  preserve  its  balance.  The 
animal  seems  awkward  to  us,  perhaps,  but  it  is  possible 


164  DOCTRINE  OF  EVOLUTION 

that  the  human  method  of  balancing  the  body  by 
vigorously  swinging  the  arms  might  seem  quite  as  awk- 
ward to  a  gibbon  as  its  grotesque  posture  does  to  us. 

The  orang-outang  comes  next  in  this  series.  It 
inhabits  the  islands  of  Borneo  and  Sumatra,  where  we 
find  two  distinct  species.  It  is  a  reddish  colored  animal 
standing  about  four  feet  four  inches  high,  with  rather 
long  hair.  It  is  bulky,  slow  and  deliberate  in  action, 
and  when  it  walks  in  a  semi-erect  position  it  rests  its 
knuckles  upon  the  ground,  swinging  its  long  arms  as 
crutch-like  supports.  Like  the  gibbon,  it  does  not 
walk  upon  all  four  feet  in  the  way  that  the  monkeys  and 
baboons  do,  and  we  find  in  the  still  further  development 
of  the  brain  and  the  higher  arch  of  the  cranium  the 
reasons  for  its  semi-erectness.  It  cannot  remain  with 
its  hands  and  feet  upon  the  ground  and  bend  back  its 
head  so  as  to  direct  its  vision  forward. 

The  chimpanzee  of  intertropical  Africa  brings  us  to 
a  still  less  monkey-hke  and  more  manlike  stage.  This 
creature  attains  the  height  of  five  feet,  which  is  more 
than  that  of  some  of  the  lower  races  of  man.  It  possesses 
large  ears  and  heavy  overarching  brows ;  its  thumb 
and  great  toe  are  more  like  those  of  man,  though  its 
foot  is  still  practically  a  hand.  Its  lower  limb  curves 
like  those  of  the  other  apes,  and  its  soles  are  turned  to- 
ward one  another;  in  brief,  it  is  naturally  bow-legged, 
a  character  that  adapts  it  for  a  tree-climbing  life. 
This  animal  also  is  nearly,  though  not  quite,  erect. 
It  shows  a  most  marked  advance  in  the  matter  of  the 
brain,  for  the  cerebrum  is  richly  folded  or  convoluted, 
and  with  this  higher  degree  of  physical  complexity  is 
correlated  its  superior  intelligence;    it  is  well  known 


EVOLUTION  OF  THE  HUMAN  SPECIES         165 

that  chimpanzees  can  be  taught  to  wear  clotliing  and 
to  use  a  cup  and  spoon  and  bowl  hke  a  human  child. 
Indeed,  in  mental  respects,  the  chimpanzee  surpasses 
all  of  the  other  mammalia,  with  the  sole  exception  of 
man.  An  eminent  psychologist  has  stated  that  it  is 
about  the  equal,  in  mental  ability,  of  a  nine  months' 
old  human  infant. 

The  last  form  among  the  apes,  the  gorilla,  is  one  that 
brings  us  to  a  realization  of  our  own  human  physical 
degeneracy.  The  animal  lives  in  West  Equatorial 
Africa,  and  it  is  a  veritable  giant  in  bulk,  though  its 
height  may  not  exceed  five  feet  six  inches.  The  heavy 
ridges  over  the  eyes,  the  upturned  nostrils  and  triangular 
nose,  place  it  near  to  the  orang-outang,  but  it  is  superior 
to  that  form  in  its  relatively  greater  brain-box,  and  in 
the  fact  that  its  heavy  lower  jaws  do  not  protrude  so 
greatly.  It,  too,  is  semi-erect,  so  that  the  line  of  the 
vertebral  axis  makes  an  angle  with  the  plane  of  the 
ground  of  about  seventy  degrees.  Its  anterior  limbs, 
or  arms,  are  again  very  long  and  bulky ;  and  like  the 
chimpanzee,  it  rests  its  knuckles  upon  the  ground  in 
walking. 

It  is  a  short  step  further  to  the  human  organism, 
whose  brain  has  become  larger  and  more  complex,  with 
a  corresponding  advance  in  the  functional  powers  of 
reason  and  the  like  that  owe  their  existence  to  the  im- 
proved structural  basis.  After  what  has  l)een  said 
earlier  regarding  the  relation  between  the  erect  attitude 
in  walking  and  the  increased  size  of  the  cranial  part  of 
the  skull  as  compared  with  the  face,  it  will  not  bo  difli- 
cult  to  see  how  inevitably  the  former  is  the  result  of 
the  latter.     Should  we  get  upon  the  ground  ui)ou  our 


166  DOCTRINE  OF   EVOLUTION 

hands  and  knees  in  the  position  of  a  tailed  monkey, 
the  eyes  look  straight  into  the  ground,  for  the  bulging 
cranium  has  pushed  out  over  the  jaws  and  face  so  that 
they  lie  under  the  brain-case  instead  of  in  front.  A 
person  in  this  position  can  bend  back  the  head  so  as  to 
look  ahead,  but  the  strain  is  too  great  for  comfort. 
Rising  to  the  knees,  and  lifting  the  hands  from  the 
ground,  a  feeling  of  ease  at  once  succeeds  that  of  tension. 
In  the  course  of  evolution  accomplished  primarily  by 
the  increase  of  the  higher  portions  of  the  brain,  the 
erect  position  has  been  assumed  gradually  and  naturally, 
and  to  maintain  it  has  necessitated  many  other  changes 
in  skeleton  and  muscles;  for  example,  the  pelvis  has 
broadened  to  support  the  intestines,  which  bear  down- 
wards instead  of  upon  the  abdominal  walls ;  a  double 
curve  has  arisen  in  the  axis  of  the  vertebral  column, 
giving  an  easier  balance  to  the  upper  part  of  the  body 
and  the  head.  Countless  structures  of  the  human 
frame  testify  to  an  originally  four-footed  position  and  to 
a  rotation  of  the  longer  axis  through  an  angle  of  ninety 
degrees,  as  evolution  has  produced  the  human  type. 

The  conclusion  that  the  human  brain  has  made 
mankind  is  thus  established  as  one  of  fundamental 
importance.  Proceeding  further,  we  learn  that  this 
organ  proves  to  be  essentially  the  same  as  the  brain 
of  lower  primates ;  it  does  not  gain  its  greater  size  and 
efficiency  by  the  origination  of  wholly  new  and  unique 
parts,  but  solely  by  the  further  elaboration  of  the  ones 
present  in  lower  forms.  In  a  word,  it  is  only  a  differ- 
ence in  degree  and  not  in  essential  kind  that  separates 
man  from  the  apes  and  other  primates.  Human  nature 
is  animal  nature,  and  human  structure  is  animal  struc- 


EVOLUTION   OF  THE  HUM.VN   SPECIES  167 

ture,  for  nowhere  can  final  and  absolute  differences  be 
found.  This  does  not  mean  that  no  differences  appear, 
for  it  would  be  absurd  to  contend  that  man  and  the 
apes  are  identical  in  every  respect ;  but  it  does  mean 
that  the  resemblances  are  fundamental  and  compre- 
hensive, and  any  details  of  dissimilarity  are  in  the 
degree  of  complexity  only.  The  supreme  place  in 
nature  attained  by  man  is  therefore  due  to  progressive 
evolution  in  the  nervous  system.  The  other  systems 
have  degenerated  to  a  greater  or  less  degree,  but 
such  regressive  changes  are  more  than  compensated 
for  by  the  superior  control  exerted  by  the  improved 
brain.  In  purely  physical  and  mechanical  respects, 
the  human  body  is  a  degenerate  as  compared  with  a 
gorilla ;  the  arm  of  the  latter  is  more  powerful  than 
the  lower  limb  of  the  former,  while  the  gorilla's  chest 
is  more  than  twice  as  broad  as  the  human,  and  more 
than  four  times  as  capacious.  It  is  not  through 
superior  physique,  but  by  superior  ability  to  direct  the 
activities  of  his  body,  that  man  excels  in  the  struggle  for 
existence  with  the  lower  animals. 


Moreover,  the  human  body  is  a  veritable  museum  of 
rare  and  interesting  relics  of  antiquity.  This  charac- 
terization is  justified  by  those  vestigial  and  rudimentary 
structures  that  represent  organs  of  value  to  human 
relatives  among  the  lower  animals,  though  thoy  i^lay  a 
less  active  part  at  the  present  time  in  human  economy. 
There  is  scarcely  a  single  system  that  does  not  exhibit 
many  or  fewer  of  these  rudimentary  structures,  but  only 
a  few  need  be  specified.     As  compared  with  those  of  the 


168  DOCTRINE  OF  EVOLUTION 

apes,  the  human  wisdom  teeth  are  degenerate ;  in  the 
gorilla  they  are  cut  at  the  same  time  as  the  other  molars  ; 
and  in  the  lower  human  races  they  com.e  through  the 
gums  in  early  youth,  while  in  the  more  advanced 
Caucasic  races  they  are  cut  only  in  later  life  or  not  at 
all.  The  reduced  vermiform  appendix  of  man,  a  source 
of  much  ill  health,  is  another  structure  that  is  a  counter- 
part of  a  relatively  larger  and  useful  part  of  the  digestive 
tract  in  the  lower  primates  and  other  animals.  Further- 
more, the  human  tail  is  a  reality,  not  a  fiction.  Now 
and  then  an  individual  is  born  with  a  tail  that  may 
reach  a  length  in  later  life  of  eight  or  ten  inches ;  such 
structures  are,  of  course,  abnormal.  But  in  every  nor- 
mal human  being  there  is  a  series  of  little  bones  at  the 
lower  end  of  the  vertebral  column,  constituting  the 
coccyx,  and  this  is  just  where  the  abbreviated  tail  of 
the  ape  and  the  still  longer  prehensile  tail  of  the  mon- 
key arises  from  the  body.  Unless  the  coccyx  is  a  tail, 
what  can  it  be?  And  if  it  does  not  represent  a  re- 
duced counterpart  of  the  tails  of  other  mammals,  what 
does  it  represent  ? 

Many  of  the  vestigial  structures  of  man  appear  more 
clearly  in  infancy  and  in  embryonic  development. 
The  human  embryo  possesses  a  complete  coat  of  hair, 
called  the  lanugo,  which  usually  disappears  before  birth. 
This  hair  cannot  be  regarded  as  any  less  significant 
than  the  coat  of  hair  which  the  infant  whale  possesses ; 
it  means  a  completely  haired  ancestor.  The  elements 
of  this  coat  are  arranged  precisely  as  they  are  in  the 
apes ;  upon  the  arm,  for  example,  they  point  from 
shoulder  to  elbow  and  from  wrist  to  elbow.  Unless 
the  anterior  limb  of  the  hairy  human  ancestor  was  held 


EVOLUTION   OF  THE   HUMAN   SPECIES  169 

in  the  position  of  the  cUmbing  ape's,  this  arranp;oment 
would  be  disadvantageous,  for  the  hair  as  a  rain-shed- 
ding thatch  would  be  effective  only  upon  the  upper  arm, 
while  the  hairs  upon  the  forearm  would  catch  the 
rain.  In  a  word,  this  vestigial  coat  indicates  in  the 
clearest  possible  manner  that  the  ancestor  of  the  human 
species  was  not  only  hairy,  but  also  arboreal  in  its  mode 
of  life. 

Every  human  infant  is  bow-legged  at  birth,  and  the 
natural  position  of  its  curved  limbs  is  like  that  of  the 
gorilla's,  for  the  soles  of  the  feet  are  turned  toward  one 
another.  Again,  the  so-called  great  toe  is  at  first  shorter 
than  the  others,  and  for  a  time  it  retains  the  power  of 
free  movement  that  indicates  a  handlike  character  of 
the  lower  limb  in  the  ancestor.  Many  savage  human 
races,  however,  whose  feet  remain  unshod,  make  use  of 
the  primitive  grasping  power  of  the  foot  which  the 
higher  races  lose  completely.  An  Australian  and  Poly- 
nesian can  pick  up  small  objects  with  the  foot  very 
much  as  we  may  with  the  hand. 

Among  the  wonderful  reminiscent  characters  dis- 
played by  the  human  infant  is  the  firm  clasping  power 
of  the  hand,  which  it  possesses  for  a  time  after  bii'th 
and  which  enables  it  to  hang  suspended  for  several 
minutes  from  a  stick  placed  in  its  grasp.  The  muscles 
which  enable  the  infant  to  do  this  gradually  dwindle, 
so  that  the  two-year-old  child  can  hang  suspended  for 
only  a  few  seconds.  This  grasping  muscle  is  a  heritage 
from  the  ape,  where  there  is  an  obvious  necessity  for  the 
newborn  individual  to  have  a  firm  hold  upon  the  hairy 
coat  of  its  tree-climbing  mother.  WTien  the  newborn 
child  hangs  in  this  way,  it  bends  its  curved  lower  limbs 


170  DOCTRINE   OF  EVOLUTION 

SO  that  the  soles  of  the  feet  are  turned  toward  one  an- 
other, thus  increasing  its  resemblance  to  the  ape. 

Let  us  realize  that  these  curious  relics  found  in  so 
many  places  in  the  framework  of  man  are  not  unique,  and 
that  they  are  reduced  counterparts  of  larger  and  more 
valuable  structures  in  the  ape.  Unless  evolution  is  true, 
they  have  absolutely  no  sensible  reasons  for  existence. 
Science  prefers  the  evolutionary  explanation  of  their 
occurrence  because  this  explanation  is  more  in  harmony 
with  the  facts  known  about  other  organisms,  and  it  is 
more  reasonable  than  any  other. 


When  we  dealt  with  the  general  doctrine  of  natural 
transformation,  it  appeared  that  the  evidence  of  embry- 
ology was  in  many  respects  more  cogent  and  conclusive 
than  that  derived  from  the  comparative  study  of  animal 
structures.  In  the  case  of  man,  as  before,  no  one  could 
demand  any  surer  or  more  convincing  proof  that  an 
organic  mechanism  with  one  structure  can  change  into 
an  organic  mechanism  with  a  different  structure,  than 
the  obvious  facts  of  development.  The  embryo,  which 
is  not  an  infant  or  an  adult,  becomes  an  infant  which 
must  work  its  way  onward  by  the  gradual  accumula- 
tion of  slight  changes  here  and  there  and  everywhere  in 
its  anatomy,  until  it  becomes  mature.  Each  and  every 
one  of  us  has  actually  undergone  the  process  of  organic 
change  in  becoming  what  we  are,  and  we  cannot  deny 
the  reality  of  such  a  process  without  challenging  the 
evidence  of  our  senses. 

When  the  full  import  of  this  history  is  realized,  and 
when  we  look  further  into  the  nature  of  these  prelim- 


EVOLUTION   OF  THE  HUMAN   SPECIES  171 

inary  conditions  through  which  the  human  organism 
passes  in  development,  we  are  forcibly  impressed  by 
other  facts  than  the  one  to  which  I  have  cUrected  your 
attention,  for  not  only  do  we  find  natural  transforma- 
tion, as  in  the  other  mammals,  but  the  embryonic  stages 
are  marvelously  similar  to  the  earlier  conditions  in' 
other  mammals.  Not  very  long  before  birth  tlie  human 
embryo  is  strikingly  similar  to  the  embryo  of  the  ape ; 
still  earlier,  it  presents  an  appearance  very  Uke  that  of 
the  embryos  of  other  mammals  lower  in  the  scale,  like  the 
cat  and  the  rabbit,  —  forms  which  comparative  anat- 
omy independently  holds  to  be  more  remote  relatives 
of  the  human  species.  Indeed,  as  w^e  trace  back  the  still 
earlier  history,  more  and  more  characters  are  found 
which  are  the  common  properties  of  wider  and  wider 
arrays  of  organisms,  for  at  one  time  the  embryo  exhibits 
gill-slits  in  the  sides  of  its  throat  which  in  all  essential  re- 
spects are  just  Uke  those  of  the  embr3'os  of  birds  and 
reptiles  and  amphibia,  as  well  as  of  other  embryo  mam- 
mals ;  and  these  gill-slits  are  furthermore  like  those 
of  the  fishes  which  use  them  throughout  Hfe.  All  the 
other  organic  systems  exhibit  everywhere  the  common 
characteristics  in  which  the  embryos  of  the  so-called 
higher  animals  agree  with  one  another  and  with  the 
adult  forms  among  lower  creatures  ;  the  human  embryo 
possesses  a  fishlike  heart  and  brain  and  primitive  back- 
bone, fishlike  muscles  and  alimentary  tract.  Can  we 
reasonably  regard  these  resemblances  as  indications  of 
anything  else  but  a  community  of  ancestry  of  the  forms 
that  exhibit  them? 

Yet  a  still  more  wonderful  fact  is  revealed  by  the 
study  of  the  very  earliest  stages  of  individual  develop- 


172  DOCTRINE  OF  EVOLUTION 

ment.  The  human  embryo  begins  its  very  existence  as 
a  single  cell,  —  nothing  more  and  nothing  less  ;  in  gen- 
eral structure  the  human  egg,  like  the  eggs  of  all  other 
many-celled  organisms,  is  just  one  of  the  unitary  build- 
ing blocks  of  the  entire  organic  world.  And  yet  the 
egg  may  ultimately  become  the  adult  man.  Does  this 
mean  that  man  and  all  the  other  higher  forms  have 
evolved  from  protozoa  in  the  course  of  long  ages? 
Science  asks  if  it  can  mean  anything  else.  When  the 
comparative  anatomist  bids  us  look  upon  the  wide  and 
varied  series  of  adult  animals  lower  than  man  as  his 
relatives,  because  they  display  similar  structural  plans 
beneath  their  minor  differences,  it  may  be  difficult  at 
first  to  obey  him.  But  in  the  brief  time  necessary  for 
the  human  egg  to  develop  into  an  adult,  the  entire 
range  is  compassed  from  the  single  cell  to  the  highest 
adult  we  know.  There  are  no  breaks  in  the  series 
of  embryonic  stages  like  those  between  the  diverse 
adult  animals  of  the  comparative  array.  I  do  not  think 
we  could  ask  nature  for  more  complete  proof  that  human 
beings  have  evolved  from  one-cell  ancestors  as  simple 
as  modern  protozoa  beyond  the  obvious  facts  of  human 
transformation  during  development.  They  at  least 
are  real  and  not  the  logical  deductions  of  reason ;  yet 
their  very  reality  and  familiarity  render  us  blind  to  the 
deeper  meaning  revealed  to  us  only  when  science  places 
the  facts  in  intelligible  order. 


And  now,  in  the  third  place,  we  may  look  to  nature 
for  fossil  evidence  regarding  the  ancestry  of  our  species. 
Much  is  known  about  the  remains  of  many  kinds  of 


EVOLUTION  OF  THE  HUMAN  SPECIES  173 

men  who  lived  in  prehistoric  times,  but  we  need  con- 
sider here  only  one  form  which  lived  long  before  the 
glacial  period  in  the  so-called  Tertiary  times.  In  1894 
a  scientist  named  Dubois  discovered  in  Java  some  of  the 
remains  of  an  animal  which  was  partly  ape  and  partly 
man.  So  well  did  these  remains  exhibit  the  characters 
of  Haeckel's  hypothetical  ape-man,  Pithecanthropus, 
that  the  name  fitted  the  creature  like  a  glove.  Spe- 
cifically, the  cranium  presents  an  arch  which  is  inter- 
mediate between  that  of  the  average  ape  and  of  the 
lowest  human  beings.  It  possessed  protruding  brows 
like  those  of  the  gorilla.  The  estimated  brain  capacity 
was  about  one  thousand  cubic  centimeters,  four  hundred 
more  than  that  of  any  known  ape,  and  much  less  than 
the  average  of  the  lower  human  races.  Even  without 
other  characters,  these  would  indicate  that  the  animal 
was  actually  a  '' missing  link"  in  the  scientific  sense, 
—  that  is,  a  form  which  is  near  the  common  progenitors 
of  the  modern  species  of  apes  and  of  man.  We  would 
not  expect  to  find  a  missing  link  that  was  actually 
intermediate  in  all  respects  between  modern  apes  and 
modern  men,  any  more  than  we  should  look  for  actual 
connecting  bands  of  tissue  between  any  two  leaves 
upon  a  tree.  A  missing  link,  in  the  true  sense,  is  Uke 
a  bud  of  earlier  years  which  stood  near  the  point  from 
which  two  twigs  of  the  present  day  now  diverge.  So 
Pithecanthropus  is  a  part  of  the  chain  leading  to  man, 
not  far  from  the  place  where  the  human  line  sprang 
from  a  lower  primate  ancestor. 

Of  the  fossil  remains  of  true  prehistoric  men.  little 
need  be  said.  We  cannot  know  whether  the  races  now 
living  in  the  regions  where  these  remains  are  found  are 


174  DOCTRINE  OF  EVOLUTION 

really  the  descendants  of  the  older  types,  and  so  a  direct 
comparison  cannot  be  made.  It  is  true  that  the  brain 
capacities  of  the  man  of  Spy,  of  the  Neanderthal,  and  of 
the  English  caverns  are  lower  than  those  of  modern  civi- 
lized races,  but  the  differences  are  not  so  striking  and 
not  so  clearly  indicative  of  the  apelike  ancestor  of 
man  as  in  the  case  of  the  previous  comparison  of 
Pithecanthropus  with  apes  and  men. 


The  foregoing  facts  illustrate  the  conclusive  evidence 
brought  forward  by  science  that  human  evolution  in 
phj^sical  respects  is  true.  Even  if  we  wished  to  do  so, 
we  cannot  do  avv^ay  with  the  facts  of  structure  and 
development  and  fossil  history,  nor  is  there  any  other 
explanation  more  reasonable  than  evolution  for  these 
facts.  If  now  we  should  inquire  into  the  causes  of  this 
process,  we  would  find  again  that  the  present  study  of 
man  and  men  reveals  their  subjection  to  the  laws  of 
nature  which  accomplish  evolution  elsewhere  in  the 
organic  world. 

The  fact  of  human  variation  requires  no  elucidation ; 
it  is  as  real  for  men  as  for  insects  and  trees.  Indeed, 
some  of  the  most  significant  facts  of  variation  have  been 
first  made  out  in  the  case  of  the  human  species.  The 
struggle  for  existence  can  be  seen  in  everyday  life.  We 
cannot  doubt  its  reality  when  scores  perish  annually 
because  of  their  failure  to  withstand  the  extreme  degrees 
of  temperature  during  midwinter  and  midsummer; 
when  starvation  causes  so  many  deaths,  and  when  the 
incessant  combat  with  bacterial  enemies  alone  brings 
the  list  of  casualties  on  the  human  side  in  our  own 


EVOLUTION   OF  THE  HUMAN  SPECIES         175 

country  to  more  than  two  hundred  and  fifty  thousand  a 
year.  As  in  nature  at  large,  the  more  unfit  are  eUmi- 
nated  as  a  result  of  this  struggle,  while  the  more  adaj)ted 
succeed.  In  the  long  run,  that  particular  a])ijhcant  for 
a  clerkship  or  any  other  work  who  may  be  the  more 
fitted  is  the  one  who  gets  it.  While  the  severity  of 
competition  may  be  somewhat  mitigated  as  the  result 
of  social  organization,  and  while  our  altruistic  charitable 
institutions  enable  many  to  prolong  a  more  or  less 
efficient  existence,  the  struggle  for  existence  cannot  be 
entirely  done  away  with.  Heredity  also  is  a  real  human 
process,  and  it  follows  the  same  course  as  in  animals  at 
large ;  as  in  the  case  of  variation,  some  of  the  funda- 
mental laws  of  its  operation  have  been  first  worked  out 
in  the  case  of  human  phenomena,  and  have  been  found 
subsequently  to  be  of  general  application. 

Reverting  to  the  specific  question  as  to  the  earliest 
divergence  of  man  from  the  apes,  we  can  readily  see  how 
the  superior  development  of  the  ape-man's  brain  gave 
him  a  great  advantage  over  his  nearest  competitors, 
and  how  truly  human  ingenuity  enabled  the  earliest 
men  to  employ  weapons  and  crude  instruments  instead 
of  brute  force.  Thus  the  gap  between  men  and  apes 
widened  more  and  more,  as  reasoning  power  increased 
through  successive  generations.  This  is  another  aspect 
of  the  statement  that  the  supreme  position  of  man  ha,s 
been  gained,  not  by  superior  organization  in  physical 
respects  outside  of  the  nervous  system,  l)ut  by  the 
superior  control  of  human  organization  by  the  higher 
organs  of  this  system. 

The  unity  of  nature  and  of  its  processes  is  established 
more  and  more  surely  as  the  naturalist  classifies  the 


176  DOCTRINE  OF  EVOLUTION 

facts  of  structure,  development,  fossil  history,  and 
evolutionary  method.  Our  own  species  is  not  unique  ; 
it  takes  its  high  place  among  other  organic  forms 
whose  lives  are  controlled  in  every  way  by  the  uniform 
consistent  laws  of  the  world. 


The  physical  evolution  of  human  races  is  the  next 
major  division  of  the  large  subject  before  us.  Hereto- 
fore the  obvious  differences  displayed  by  various  races 
have  been  disregarded  and  the  species  has  been  treated 
as  a  unit,  in  order  that  its  evolution  from  pre-human 
ancestors  might  be  made  clear.  Knowing  now  how  the 
facts  of  structure  show  that  the  supreme  position  of 
our  kind  has  been  attained  mainly  as  the  result  of  the 
progressive  elaboration  of  the  higher  portions  of  the 
brain,  and  not  because  new  and  unique  structures  have 
been  developed,  we  are  prepared  to  turn  our  attention 
to  the  diverse  characteristics  of  human  races  ;  and  during 
this  inquiry  anatomical  matters  will  still  be  the  only 
ones  to  be  reviewed.  The  intellectual  and  social  char- 
acters of  numerous  races  belong  to  the  category  of  physi- 
ological or  functional  phenomena,  which  are  to  receive 
due  consideration  at  a  later  time.  It  is  the  meaning 
of  the  facts  of  racial  diversity  for  which  we  are  now 
to  look. 

For  many  reasons  this  subject  is  more  difficult  to 
describe  in  a  concise  outline  than  those  taken  up  before. 
It  is  true  that  every  one  is  familiar  with  different  types 
of  human  beings,  such  as  the  Negro  and  Japanese  and 
Chinese,  while  furthermore  the  obvious  differences 
between  such  races  as  the  Norwegian  and  Italian  are 


EVOLUTION   OF  THE  HUMAN  SPECIES  177 

sufficiently  marked  to  strike  the  attention  of  any  one 
who  looks  about  at  his  fellow-passengers  in  a  crowded 
street  car.  But  few  indeed  have  a  comprehensive 
knowledge  of  the  wider  range  of  racial  variaticjn  in 
which  these  familiar  examples  find  their  place.  Anthro- 
pology, or  the  science  of  mankind,  is  a  large  and  well- 
organized  department  of  knowledge,  dealing  with  the 
entire  array  of  structural  and  physiological  characters 
of  all  men.  One  of  its  subdivisions,  anthropometry,  is 
almost  an  independent  discipline  with  methods  of  its 
own ;  it  describes  the  characteristics  of  human  races  as 
these  are  determined  by  statistical  methods  of  a  some- 
what technical  nature.  There  is  still  another  science, 
ethnology,  which  deals  more  particularly  with  institu- 
tions, customs,  beliefs,  and  languages  rather  than  with 
physical  matters,  although  it  is  clear  that  ethnology 
and  anthropology  cannot  be  sharply  separated,  and  that 
each  must  employ  the  results  of  the  other  for  its  own 
particular  purposes. 

Because  men  have  always  been  interested  in  the  study 
of  themselves,  the  subject  of  racial  evolution  is  literally 
enormous,  and  the  attempt  to  give  anything  like  a 
complete  description  of  what  is  known  would  obviously 
be  futile.  But  it  is  possible  to  obtain  a  clear  conception 
of  certain  of  the  fundamental  principles  that  fall  into 
line  with  the  other  parts  of  the  doctrine  of  organic  evo- 
lution with  which  we  have  now  become  acquainted. 
The  main  questions,  therefore,  may  be  stated  in  simple 
terms.  The  first  deals  with  the  evidences  as  to  the 
reality  of  evolution  during  the  historical  and  prehistoric 
development  of  the  various  types  of  man  from  earlier 
common  ancestors ;   the  second  asks  whether  the  lines 

N 


178  DOCTRINE  OF  EVOLUTION 

of  racial  evolution  are  further  continuations  of  the  line 
leading  from  ape-like  ancestors  to  the  human  species  as 
a  type.  In  order  to  give  the  proper  perspective,  it  will 
be  well  to  state  at  the  present  juncture,  first,  that  the 
various  kinds  of  men  do  not  vary  from  each  other  in  a 
chance  manner  so  as  to  show  all  possible  types  and 
varieties,  but  that  they  fall  into  natural  groups  or 
families  distinguished  by  certain  common  character- 
istics, just  as  do  all  other  kinds  of  species  of  animals ; 
in  the  second  place,  it  appears  that  some  of  the  dif- 
ferences between  the  races  denoted  higher  on  struc- 
tural accounts  and  the  lowest  forms  of  man  are  of  the 
same  nature  as  those  observed  in  the  review  of  the 
various  species  of  primates  from  the  lemurs  to  man. 


It  is  best  to  look  at  the  whole  question  in  a  very  simple 
and  common-sense  way  before  undertaking  an  extended 
examination  of  the  details  of  human  diversity.  The 
most  casual  survey  of  the  peoples  that  we  know  best 
because  of  our  own  individual  nearness  to  them  enables 
us  to  realize  that  the  races  now  upon  the  earth  have  not 
existed  forever  and  ever,  or  even  for  the  age  of  6000 
years  as  contended  by  Archbishop  Ussher.  They  have 
all  come  into  existence  as  such,  and  they  differ  from 
their  known  antecedents;  so  that. at  the  very  outset 
common-sense  leads  us  to  accept  evolution  as  true,  if 
we  admit  that  human  races  have  changed  during  the 
course  of  recent  centuries.  We  know,  for  example,  that 
the  so-called  Mexicans  of  to-day  are  a  people  produced 
by  a  fusion  of  Spanish  conquerors  and  Indian  aborig- 
ines ;  the  Mexican  is  neither  Spaniard  nor  Indian,  though 


EVOLUTION  OF  THE  HUMAN  SPECIES  170 

he  may  resemble  both  in  certain  respects  ;  he  is  a  prod- 
duct  of  natural  evolution,  accomplished  in  this  case  by 
an  amalgamation  of  two  contrasted  types.  When  we 
speak  of  the  American  people,  we  must  realize  that  it  too 
has  come  into  existence  as  such,  and  even,  indeed,  that 
it  is  in  the  actual  process  of  evolution  at  the  present 
time.  The  various  foreign  elements  that  have  been 
added  during  the  last  few  decades  by  the  hundreds  of 
thousands  are  becoming  merged  with  the  people  who 
preceded  them,  just  as  the  Dutch  and  the  French  and 
the  English  coalesced  during  the  days  of  early  settlement 
to  form  the  young  American  nation.  Perhaps  most  of 
us  call  ourselves  Anglo-Saxon,  but  we  arc  in  reality  some- 
what different  even  in  physical  respects  from  the  Eng- 
lishmen of  Queen  Elizabeth's  time,  who  alone  deserved 
the  name  Anglo-Saxon.  This  very  term  indicates  an 
evolution  of  a  type  that  differs  from  both  the  Angles 
and  the  early  Saxons  of  King  Alfred's  age.  These  are 
simple  examples  which  illustrate  many  features  of  the 
universal  history  of  human  races  wherever  they  are  to 
be  found.  Even  in  the  comparatively  peaceful  times 
of  our  modern  era  the  history  of  any  race  is  a  veritable 
turmoil  of  constant  changes ;  conquerors  impress  their 
characters  upon  the  vanquished,  while  the  victors  often 
adopt  some  of  the  features  of  the  conquered.  Colonies 
split  off  from  the  mother  nation  to  follow  out  their 
destinies  under  other  conditions.  Nowhere  does  the 
naturalist  find  evidence  of  long-established  permanence, 
or  an  unent wined  course  of  an  uninterrupted  and  un- 
modified line  of  racial  descent. 

It  is  the  task  of  the  student  of  human  evolution  to 
unravel  the  tangled  threads  of  human  histories.     The 


180  DOCTRINE  OF  EVOLUTION 

task  is  relatively  simple  when  it  is  concerned  with  recent 
times  where  the  aid  of  written  history  may  be  sum- 
moned ;  but  when  the  events  of  remote  and  prehistoric 
ages  are  to  be  placed  in  order,  the  difficulties  seem  well- 
nigh  insuperable.  All  is  not  known,  nor  can  it  ever  be 
known ;  but  wherever  facts  can  be  established,  science 
can  deal  with  them.  By  a  study  of  the  present  races 
of  mankind,  much  of  their  earlier  history  can  be  worked 
out,  for  their  genetic  relations  may  be  determined  by 
employing  the  principle  that  likeness  means  consanguin- 
ity. Let  us  suppose  an  alien  visitor  to  reach  our  planet 
from  somewhere  else;  if  he  were  endowed  with  only 
ordinary  human  common-sense,  he  would  very  soon 
ascertain  the  common  origin  of  the  English-speaking 
people  in  Canada,  the  United  States,  Australia  and 
New  Zealand,  South  Africa,  and  many  other  places. 
Even  if  he  could  not  understand  a  word  of  the  English 
language,  he  would  be  justified  in  regarding  them  all  as 
the  descendants  of  common  ancestors  because  they 
agree  in  so  many  physical  qualities.  The  anthropologist 
works  according  to  the  same  common-sense  principle, 
obtaining  results  that  find  no  explanation  other  than 
evolution  when  the  varying  characters  that  are  used  to 
determine  social  relationship  are  properly  classified  and 
related.  It  is  to  these  characters  that  we  must  now 
give  some  attention. 


The  average  stature  of  adults  varies  in  different  races 
from  four  feet  one  inch  in  certain  blacks  to  nearly  six 
feet  and  seven  inches,  as  among  the  Patagonians. 
These   are  the  extreme  values   for  normal   averages, 


EVOLUTION   OF  THE   HUMAN   SPECIES  181 

although  dwarfs  only  fifteen  inches  high  have  been 
known,  while  '^giants  "  sometimes  occur  with  a  height 
of  nine  feet  and  five  inches.  Such  individuals  are  of 
course  rare  and  abnormal,  and  are  not  to  be  taken 
into  account  in  establishing  the  average  stature  of 
a  race  for  use  in  comparison  with  that  of  another 
group. 

The  color  of  the  skin  is  another  criterion  of  racial 
relationship,  though  it  is  more  variable  in  races  of  com- 
mon descent  than  we  are  wont  to  assume.  We  are 
familiar  with  the  fair  and  florid  skin  of  the  northern 
European,  the  fair  and  pale  skin  in  middle  and  southern 
Europe,  the  coppery  red  of  the  American  Indian,  the 
brown  of  the  Malay,  of  the  Polynesian  and  of  the  Moor, 
the  yellowish  cast  of  the  Chinese  and  Japanese,  and 
the  deeper  velvety  black  of  the  Zulu ;  but  it  has  been 
found  that  many  of  the  close  relatives  of  the  black  are 
lighter  in  skin  color  than  some  of  our  Caucasian  rela- 
tives, so  that  this  character  cannot  be  taken  by  itself 
as  a  single  criterion  of  racial  affinity. 

Perhaps  the  most  conservative  and  most  reliable 
character  that  serves  for  the  broad  classification  of  the 
human  races  is  the  shape  of  the  individual  hairs  of  the 
head.  We  are  familiar  with  the  straight  lank  hair  of 
the  Mongolian  peoples  and  of  the  various  tribes  of 
American  Indians,  in  whom  the  hair  possesses  these 
peculiarities  because  each  element  grows  as  a  nearly 
perfect  cylinder  from  the  cells  of  the  skin  at  the  bottom 
of  a  tiny  pit  or  hair-follicle.  The  familiar  wavy  hair 
of  white  men  owes  its  character  to  the  fact  that  the 
individual  elements  are  formed  by  the  skin,  not  as  j)encil- 
like  rods,  but  as  flattened  cylinders.     They  are  oval  or 


182  DOCTRINE  OF  EVOLUTION 

elliptical  in  cross-section,  and  when  they  emerge  from 
the  skin  they  grow  into  a  long  spiral.  If,  now,  the  hair 
is  formed  as  a  very  much  flattened  rod  about  one-half 
as  wide  in  one  diameter  as  in  the  other,  it  curls  into  a 
very  tight  close  spiral  and  gives  the  frizzly  or  woolly 
head-covering  of  the  Papuan  and  of  the  Negro. 

In  the  next  place,  the  shape  of  the  cranium  is  a  char- 
acter of  much  value.  This  is  determined  as  the  propor- 
tion between  the  transverse  diameter  of  the  skull  above 
the  ears  to  the  long  diameter,  namely,  the  line  that  runs 
from  the  middle  of  the  brow  to  the  most  posterior  point 
of  the  skull.  In  the  so-called  '4ong-headed  "  or  doli- 
chocephalic races,  the  proportion  is  seventy-five  to  one 
hundred,  while  in  those  forms  that  have  more  rounded 
or  brachy cephalic  heads,  like  the  Polynesian  and  the 
black  pygmy,  the  relation  is  eighty-three  to  one  hundred. 
The  cranial  capacity  again  varies  considerably,  from 
nine  hundred  cubic  centimeters  to  twenty-two  hundred 
cubic  centimeters.  Many  striking  variations  are  also 
found  in  the  projection  of  the  jaws.  A  line  drawn 
from  the  lower  end  of  the  nose  to  the  chin  makes  a 
certain  angle  with  the  line  drawn  from  the  chin  to  the 
posterior  end  of  the  lower  jaw;  if  the  jaw  projects  very 
greatly,  this  angle  will  be  much  less  than  when  they  do 
not.  In  most  of  the  Caucasian  peoples,  the  lines  meet 
at  an  angle  of  eighty-nine  degrees,  or  very  nearly  a  right 
angle,  but  in  some  of  the  lower  races  the  figure  may  be 
only  fifty-one  degrees.  Additional  characters  of  the 
teeth  and  of  the  palate  are  also  taken  into  account,  and 
have  proved  their  utility.  Finally,  the  nose  exhibits 
a  wide  range  of  variation  from  the  small  delicate  feature 
of  the  Chinaman  to  the  large,  well-arched  nose  of  the 


EVOLUTION   OF  THE  HUMAN   SPECIES  183 

Indian.  It  may  be  hollowed  out  at  the  bridge  instead 
of  arched;  again,  it  may  be  nearly  an  equilateral  tri- 
angle in  outline,  as  in  the  Veddahs,  and  the  nostrils  may 
open  somewhat  forward  instead  of  downward.  As 
many  as  fifteen  distinct  varieties  of  the  human  nose 
have  been  catalogued  by  Bertillon. 

These  are  the  principal  bodily  characters  which  the 
anthropologist  uses  to  distinguish  races  and  by  their 
means  to  determine  the  more  immediate  or  remote  com- 
munity of  origin  of  comparable  types.  Many  of  these 
characteristics,  as  indeed  we  may  already  see,  are  de- 
cidedly important  in  connection  with  the  second  problem 
specified  above,  for  in  the  case  of  the  flat  triangular 
nose  and  projecting  jaws  of  a  low  negroid  we  may 
discern  clear  resemblances  to  certain  featui'es  of  the 
apes. 


Long  before  the  doctrine  of  evolution  was  understood 
and  adopted,  students  of  the  human  races  had  been 
deeply  impressed  by  their  natural  resemblances.  As 
early  as  1672  Bernier  divided  human  beings  accord- 
ing to  certain  of  these  fundamental  similarities  into  four 
groups;  namely,  the  white  European,  the  black  African, 
the  yellow  Asiatic,  and  the  Laplander.  Linuieus,  in 
the  eighteenth  century,  included  Homo  sapieris  in  his 
list  of  species,  recognizing  four  subspecies  in  the  Euro- 
pean, Asiatic,  African,  and  Indian  of  America.  Blu- 
menbach  in  1775  added  the  Malay,  thus  giving  the  five 
types  that  most  of  us  learned  in  our  school  days.  But 
the  different  varieties  of  men  recognized  b}'  these 
observers  were  believed  to  be  created  in  their  modern 


184  DOCTRINE  OF  EVOLUTION 

forms  and  with  their  present-day  characteristics;  the 
common  character  of  skin  color  exhibited  by  any  group 
of  peoples  of  a  single  continent  was  to  them  only  a 
convenient  label  for  purposes  of  description  and  classifi- 
cation. It  was  not  until  years  later  that  fundamental 
resemblances  were  recognized  as  indicating  an  actual 
blood  relationship  of  the  races  displaying  them,  and 
therefore  of  evolution.  Since  the  doctrine  of  human 
descent  and  of  the  divergence  of  human  races  in  later 
evolution  has  been  accepted,  those  who  have  attempted 
to  work  out  fully  the  complete  ancestry  of  different 
peoples  have  found  that  no  single  character  can  be  taken 
by  itself,  while  the  various  criteria  themselves  differ  in 
reliability ;  the  color  of  the  skin  is  not  so  sure  a  guide  as 
the  character  of  the  hair  and  skull,  wherefore  the  classi- 
fications of  recent  times,  notably  those  of  Huxley  and 
Haeckel,  have  been  based  largely  upon  the  latter.  The 
latest  systems  have  been  more  rigidly  scientific  and  more 
in  accord  with  the  most  modern  conceptions  of  organic 
relationships  in  general,  as  evidenced  by  the  thorough- 
going methods  of  Duckworth  in  his  recent  treatise  on 
human  classification. 

It  now  remains  to  present  the  salient  facts  regarding 
the  genetic  relationships  of  typical  human  races, 
although  it  is  obviously  impossible  to  go  into  all  of  the 
details  of  the  subject.  But  these  are  not  essential  for 
the  main  purpose,  which  is  to  show  that  the  evolution- 
ary explanation  is  the  only  one  that  is  reasonable  and 
self-consistent.  Opinions  are  sometimes  widely  at 
variance  regarding  countless  minor  points,  but  no  an- 
thropologist of  to-day  can  be  anything  but  an  evolu- 
tionist, because  the  main  principles  upon  which  the 


EVOLUTION   OF  THE   HUMAN   SPECIES  185 

specialists  agree  fall  directly  into  line  with  those  estab- 
lished elsewhere  in  zoology.  It  seems  best  to  state 
these  principles  without  reverting  to  controversial  mat- 
ters which  fmd  their  place  in  the  monographs  of  the 
experts.  Any  comprehensive  account  such  as  that  of 
Keane,  even  if  it  may  not  give  the  final  word,  will  bo 
entirely  sufficient  to  demonstrate  how  fruitful  are  tlio 
methods  of  evolution  when  they  are  employed  for  the 
study  of  human  races,  and  indeed  how  impossible  it  is 
to  discuss  human  histories  without  finding  conclusive 
evidences  of  their  evolutionary  nature. 

The  facts  that  are  available  indicate  that  the  first 
members  of  our  species  evolved  in  an  equatorial  conti- 
nent which  is  now  submerged,  and  which  occupied  a 
position  between  the  present  continents  of  Asia  and 
Africa.  From  this  center  hordes  of  primitive  men 
migrated  to  distant  centers  where  they  differentiated 
into  three  primary  and  distinct  groups.  The  first  of 
these  was  gradually  resolved  into  the  darker-skinned 
peoples  most  of  whom  now  live  in  the  continent  of 
Africa,  although  many  dwell  also  in  the  islands  of  the 
western  Pacific  Ocean.  The  second  branch  divided 
almost  immediately  to  produce,  on  the  one  hand,  the 
Indians  of  the  new  world  and,  on  the  other,  the  yellow- 
skinned  inhabitants  of  Asia  and  other  places.  The 
third  branch  developed  as  such  in  the  neighborhood  of 
the  Mediterranean  Sea,  and  produced  the  series  of 
so-called  Caucasian  peoples,  which  are  by  far  the  most 
familiar  to  us  and  to  which  most  of  us  belong.  But 
so  early  did  the  second  branch  divide  that  there  are 
virtually  four  main  divisions  of  the  human  species  that 
are  to  be  examined  in  serial  order. 


186  DOCTRINE  OF  EVOLUTION 

It  is  best  to  begin  with  our  own  division,  because  its 
greater  familiarity  makes  it  easier  to  become  acquainted 
with  the  methods  and  results  of  anthropology,  on  the 
basis  of  facts  that  we  already  know.  Three  subordi- 
nate types  exist,  located  primarily  in  northern,  central, 
and  southern  Europe  respectively,  but  many  other  races 
dwell  elsewhere  that  are  assignable  to  one  or  another 
of  these  subdivisions.  In  northeastern  Europe  we 
find  people  such  as  the  Norwegians,  Swedes,  Danes,  and 
north  Germans,  that  average  five  feet  eight  inches  in 
height.  They  have  the  long,  wavy,  and  soft  hair  which 
is  a  general  characteristic  of  the  whole  Caucasian 
group,  although  its  light  flaxen  color  is  distinctive. 
The  blue  eye  and  florid  complexion  accompany  the 
light  color  of  the  hair.  The  skull  is  of  the  longer  type, 
the  jaws  and  forehead  are  straight  and  square,  the  nose 
is  large  and  long  without  a  distinct  arch,  and  the  teeth 
are  relatively  small.  It  is  not  so  well  known  that  the 
Scandinavian  type  is  so  closely  copied  by  many  people 
of  Asia,  such  as  the  western  Persians,  Afghans,  and 
certain  of  the  Hindus,  living  in  a  continent  that  we  are 
inclined  to  assign  to  the  Mongol  only.  In  the  posses- 
sion of  these  characters  the  Northern  Europeans  and 
other  races  specified  display  evidences  of  their  common 
ancestry  and  evolution  quite  as  conclusively  as  in  the 
case  of  the  cats  discussed  in  an  earlier  chapter  where 
the  meaning  of  essential  likeness  was  first  demonstrated. 

A  broad  zone  may  be  drawn  from  Wales,  across  Eu- 
rope and  Asia,  and  even  to  the  eastern  islands  of  the 
South  Seas,  in  which  we  find  peoples  that  are  obviously 
of  Caucasian  descent,  but  they  differ  from  the  members 
of  the  first  group  in  some  details  of  structure.     On  the 


EVOLUTION   OF  THE  HUMAN   SPECIES  187 

average  they  are  about  five  feet  five  or  six  inclics  in 
height,  the  hair  is  dark  and  wavy,  but  it  is  not  the  pencil- 
Uke  structure  of  the  Mongol.  The  complexion  is  pale, 
the  skull  is  rounder,  and  the  eyes  are  usually  brown  in 
color.  These  peoples  agree  also  in  their  volatile  tem- 
perament and  vivacious  manner  and  are  thus  markedly 
different  from  the  more  stolid  northerners.  To  this 
minor  branch  of  the  Caucasian  stock  belong  the  Welsh, 
most  of  the  French,  South  Germans  and  Swiss,  Rus- 
sians and  Poles,  Armenians,  eastern  Persians,  and  finally 
some  of  the  inhabitants  of  Polynesia.  The  last,  it  is 
true,  form  a  well-marked  group  of  darker-skinned  and 
taller  races,  but  in  spite  of  the  admixture  of  these  and 
other  unusual  features,  we  can  still  discern  the  bodily 
characters  that  supplement  their  traditions,  telling  of 
an  Asian  origin,  in  demonstrating  their  common  ances- 
try with  round-headed  Persians  and  middle  Europeans. 
Below  the  zone  of  middle  Europe  and  Asia  is  another 
broad  region  inhabited  by  the  "  Mediterranean  "  type 
of  Caucasian.  The  Spaniard,  Italian,  Greek,  and  Arab 
are  sufficiently  familiar  to  illustrate  the  distinctive 
qualities  of  this  subdivision.  These  people  have  the 
smaller  stature,  dark  hair,  dark  eyes,  and  jxiler  skin 
of  the  middle  Europeans,  but  the  skull  is  of  the  long 
instead  of  the  rounded  type.  A  well-marked  sub- 
ordinate group  is  formed  by  the  so-called  Semitic 
peoples,  such  as  the  Arabs  and  their  Ilel-jrew  relatives. 
The  Berbers  and  other  North  African  races  j^ossess  a 
darker  skin  probably  because  of  the  admixture  of 
Ethiopian  stock,  and  they,  too,  are  so  well  character- 
ized that  they  form  a  clearly  marked  outlying  group 
as  the  so-called  Hamites.     Passinc;  over  into  Asia  we 


188  DOCTRINE  OF  EVOLUTION 

ft 

find  relatives  of  the  Mediterranean  man  in  the  Dravidas 
and  Todas  of  India,  possibly  in  the  degenerate  Veddahs 
of  Ceylon,  and  finally  in  the  Ainus  or  ''  hairy  men  " 
of  some  of  the  Japanese  islands.  The  last-named 
people  certainly  possess  some  Mongolian  features, 
but  these  seem  to  have  been  added  to  a  more  funda- 
mental form  of  body  that  is  distinctly  Caucasian. 

All  of  the  races  we  have  mentioned,  together  with 
their  relatives,  may  be  compared  to  the  leaves  borne 
upon  three  branches  that  take  their  origin  from  a  single 
limb  of  the  widespread  human  part  of  the  tree.  They 
cannot  be  classified  in  any  mode  on  the  basis  of  their 
primary  and  secondary  resemblances  without  employing 
the  treelike  plan  of  arrangement,  which  to  the  man 
of  science  is  a  sure  indication  of  their  evolutionary 
relationships. 


The  people  of  the  second  or  Mongolian  group  agree  in 
certain  well-marked  characteristics  in  such  a  way  as  to 
be  well  separated  from  the  other  divisions  of  mankind ; 
these  characteristics  we  may  speak  of  as  constituting 
a  second  '^  theme,"  of  which  the  various  peoples  of  the 
group  are  so  many  variations.  To  visualize  them  we 
need  only  to  recall  the  appearance  of  the  Chinaman, 
perhaps  the  most  familiar  example  of  the  entire  series. 
Here  the  hair  is  coarse  and  black,  and  straight  because 
of  its  round  transverse  section ;  the  mustache  and 
beard  of  the  Caucasians  are  seldom  found  except  in 
later  life  ;  the  skin  is  a  fleshy  yellow  in  color  ;  the  skull  is 
round,  indeed,  it  is  one  of  the  roundest  that  we  know ; 
the  jaws  are  not  so  straight  as  in  the  Caucasian,  for 


EVOLUTION   OF  THE  HUMAN   SPECIES  189 

the  angle  at  the  point  of  the  chin  is  about  sixty-eight 
degrees.  The  cheek  bones  project  laterally,  with  greater 
or  less  prominence ;  the  nose  is  very  small,  tilted  up 
slightly  at  the  end,  and  is  usually  hollowed  instead  of 
arched.  The  eyes  are  small  and  black  in  color,  set 
somewhat  obliquely,  and  the  upper  lid  is  drawn  down 
over  the  eye  at  its  inner  corner  so  as  to  make  the  ob- 
liquity still  more  marked.  The  teeth  are  larger  than 
those  of  the  Caucasian.  Finally,  the  Mongol  is  below 
the  average  of  all  men  as  regards  height,  being  usually 
about  five  feet  four  inches  tall. 

The  original  Mongolians  probably  developed  the 
characteristic  features  we  have  just  noted  in  a  Central 
Asiatic  region,  and  then  almost  immediately  they 
divided  into  two  great  groups.  Each  of  these  evolved 
along  certain  lines  of  its  own,  one  sweeping  northward 
to  develop  into  what  are  now  called  the  Northern 
Mongols,  the  other  working  its  w^ay  eastward  and  south- 
ward to  produce  the  peoples  of  China  proper,  Indo- 
China,  and  many  parts  of  ^Malaysia.  Considering  first 
the  peoples  of  the  Northern  Mongolian  division,  we 
find  in  the  typical  Manchurian  what  is  perhaps  the 
nearest  among  modern  people  to  the  original  race. 
Spreading  northward  and  westward  from  the  middle 
Asiatic  plains,  this  great  wave  has  produced  the  nomadic 
tribes  of  Siberia,  like  the  Chukchi,  the  Buryats,and  the 
Yukaghir.  The  present  inhabitants  of  Turkestan  con- 
nect those  forms  which  have  remained  near  the  original 
home  with  the  races  of  Mongolian  origin  that  live 
farther  to  the  westward,  like  the  Turks  of  Asia.  But 
the  Mongolian  tide  originally  swept  nuich  farther  to  the 
west,  although  it  was  driven  back  later  by  conquering 


190  DOCTRINE  OF  EVOLUTION 

Caucasian  peoples;  and  it  has  left  behind  such  rem- 
nants as  the  Finlander  and  the  Laplander,  the  Bulgar, 
and  the  Magyar.  It  is  evident  that  these  western 
branches  of  the  Mongol  stock  are  not  at  all  pure  in  their 
racial  characteristics,  for  they  clearly  show  the  effects 
of  a  mixture  with  alien  European  peoples.  To  assign 
them  to  the  Northern  Mongol  division  means  only  that 
their  dominant  characteristics  are  mainly  those  of 
Mongolian  nature.  We  have  referred  the  Russians  to 
the  middle  Caucasian  division  even  though  the  Slav 
or  Tartar  infusion  is  very  great,  but  it  does  not  domi- 
nate over  the  Caucasian  peculiarities  as  it  does  in  the 
case  of  the  peoples  we  have  mentioned.  As  regards 
the  remaining  types  we  must  add  to  this  brief  list  the 
Koreans  and  the  Japanese,  the  former  being  far  purer 
in  Mongolian  nature  than  the  latter  people,  which  has 
apparently  been  affected  by  a  Malay  influence  from 
the  south. 

Turning  now  to  the  southern  Mongol,  we  find  that 
from  their  cradle  in  the  Tibetan  plateau  they  too  have 
spread  widely,  and  their  descendants  have  also  come 
to  differ  in  certain  respects  as  they  have  established 
themselves  in  other  lands.  Most  of  the  present  people 
of  Tibet  belong  to  this  section;  the  Gurkhas  of  Hin- 
dustan, the  people  of  Burma  proper,  of  Annam,  and 
Cochin  China  are  close  relatives  of  one  another  and  of 
the  more  characteristic  Mongolians  of  China  proper 
who  make  up  the  vast  bulk  of  the  population.  From 
this  stock  we  may  also  derive  the  Malays  of  Sumatra 
and  Java,-  of  Borneo  and  Celebes,  and  the  Tagals  and 
Bisayans  of  the  Philippine  Islands.  Even  the  Hovars 
and  other  tribes  of  Madagascar  may  be  referred  to  this 


EVOLUTION  OF  THE  HUMAN  SPECIES  191 

division,  for  although  in  them  the  skin  has  become 
somewhat  darker,  we  may  still  discern  the  character- 
istics which  indicate  their  common  ancestry  with  the 
Oceanic  Mongols. 


The  American  Indians  taken  collectively  constitute 
a  group  that  is  well  set  off  from  the  rest  of  mankind  by 
such  characters  as  taller  stature,  small,  straight,  and 
black  eyes,  a  large  nose  that  is  usually  bridged  or  acjui- 
line,  a  skull  of  medium  roundness,  and  the  yellow  copper 
color  of  the  skin.  The  common  origin  with  the  Mongols 
is  demonstrated  by  the  straight  and  long,  coarse,  black 
hair  and  by  the  absence  of  a  beard ;  the  mustache  also 
is  almost  always  absent. 

All  of  us  have  seen  Indians  belonging  to  the  tribes 
of  the  plains,  which  serve  as  excellent  examples  of  this 
grand  division.  Many  have  also  visited  the  homes  of 
the  Pueblo  Indians,  and  have  learned  how  uniform  is 
the  physical  appearance  of  the  tribes  living  in  various 
parts  of  the  United  States.  Indeed  throughout  all  of 
North  America  the  basic  characteristics  of  Indians 
prove  to  be  strikingly  conservative,  although  in  the 
Eskimo  there  are  some  departures  which  seem  to  indi- 
cate a  closer  connection  of  these  peoples  with  the  Mon- 
gols, probably  as  the  result  of  some  more  recent  influx 
from  the  neighboring  and  not  very  distant  region  of 
northeastern  Siberia.  Extending  our  survey  south- 
ward through  Central  America,  the  Aztecs  and  Mayas 
are  found  to  possess  many  of  the  same  characters, 
though  in  some  respects  they  are  transitional  to  the 
Caribs  of  the  northern  edge  of  South  America  and  to 


192  DOCTRINE  OF  EVOLUTION 

the  Indians  of  South  America.  Traveling  still  farther 
southward,  we  meet  the  very  tall  Patagonian,  still  an 
Indian  in  essential  respects,  and  finall}^,  the  Yahgan 
and  Alacaluf  of  the  Fuegian  region,  the  most  degenerate 
members  of  the  race.  The  last-mentioned  people  are 
dull  and  brutish  and  most  degraded  in  all  respects, 
and  stand  at  the  lowest  end  of  the  red  Indian  series 
as  regards  intellectual  ability  and  cultural  attainment. 


We  now  come  to  the  last  of  the  four  great  divisions  of 
the  human  species  which  includes  the  races  usually 
spoken  of  as  Africans  or  Ethiopians.  But  these  races 
are  by  no  means  restricted  to  the  continent  of  Africa, 
for  quite  as  typical  black  types  are  found  in  far-distant 
lands  such  as  Australia  and  many  islands  of  the  Pacific 
Ocean.  The  races  assigned  to  this  division  group  them- 
selves about  two  subordinate  types,  —  the  tall  negro 
proper  and  the  shorter  or  dwarf  negrito,  —  and  each  of 
these  has  representatives  both  in  Africa  and  in  the 
oceanic  territory. 

The  black  slaves  of  America  were  all  descended  from 
typical  negros  brought  from  the  western  part  of  Africa, 
and  they  provide  us  with  adequate  illustrations  of  Ethi- 
opians as  a  group.  In  them  the  stature  is  above  the 
average  of  men  in  general,  specifically  about  five  feet 
ten  inches.  The  short  jet-black  hair  is  strikingly  dif- 
ferent from  the  head  covering  of  the  other  great  groups 
of  human  races ;  each  individual  hair  is  so  flat  in  cross- 
section  that  it  curls  into  a  very  tight  close  spiral,  and 
this  brings  about  a  frizzly  appearance  of  the  whole  head 
covering.     There  is  little  or  no  beard,  the  skin  is  soft 


EVOLUTION   OF  THE  HUMAN   SPECIES  193 

and  velvety  and  of  various  shades  approaching  black 
in  color.  The  skull  is  long,  the  check  bones  are  small, 
but  the  most  distinctive  characteristics  of  the  head  are 
found  in  the  apelike  ridges  over  the  eyes  and  in  the 
very  broad  flat  nose  which  projects  only  slightly  and 
turns  up  so  that  the  nostrils  open  forward  to  a  marked 
degree,  while  in  the  jaws  there  is  an  astonishing  diver- 
gence from  the  Caucasian  condition  in  the  great  pro- 
trusion which  causes  the  angle  at  the  chin  to  be  about 
sixty  degrees. 

The  warlike  Zulus  and  other  peoples  of  Southern  and 
Central  Africa  are  perhaps  the  most  characteristic 
races  in  this  division.  Their  relatives  are  found  to  the 
northw^ard  as  far  as  the  Sahara  desert,  along  the  south- 
ern borders  of  which  they  have  spread  out  to  the  east- 
ward and  westward.  Fusion  with  other  races  has  taken 
place  along  this  border  so  that  man}^  of  these  northern 
tribes  are  much  lighter  than  the  Zulus  in  the  color  of 
the  skin.  But  many  relatives  of  the  taller  African  negro 
are  found  in  other  parts  of  the  world,  namel}'  in  Aus- 
tralia, and  in  New  Hebrides  and  New  Caledonia  — 
islands  to  the  north  and  east  of  this  continent.  The 
Papuan  of  New  Guinea  is  a  typical  negro  in  all  true 
respects,  with  strongly  marked  Ethiopian  character- 
istics, though  there  are  some  differences  which  are 
transitional  to  the  more  aberrant  natives  of  Melanesia, 
which  includes  many  archipelagos  like  the  Fiji,  Bis- 
marck, Marshall,  and  Solomon  islands.  I^ndoubtedly 
the  most  degenerate  member  of  the  tall  negro  division 
is  the  Australian  native,  the  so-called  ''  blackfellow." 
The  bulbous  nose  and  the  well-grown  beard  mark  him 
off  from  the  typical  stock,  but  his  obvious  relation- 


194  DOCTRINE  OF  EVOLUTION 

ship  to  this  is  indicated  by  the  low  brain  capacity,  the 
prominent  ridges  over  the  eyes,  and  the  heavy  pro- 
jecting jaws. 

Taking  up  the  other  division  of  the  so-called  Ethi- 
opian race,  constituting  the  Negrito  section,  we  may 
begin  with  its  Oceanic  members.  The  natives  of  the 
Andaman  Islands,  the  Kalangs  and  the  Sakais  of  Java 
and  neighboring  regions,  and  the  Aetas  of  the  Philip- 
pine Islands  agree  in  a  dwarfed  stature  of  four  feet  or  a 
little  over,  in  their  yellowish  brown  skin  color,  a  round 
head,  and  woolly  reddish-brown  hair.  They,  too,  pos- 
sess large  ridges  over  the  eyes  and  extremely  prominent 
jaws,  and  in  these  latter  characteristics  particularly  we 
see  evidences  of  their  relationship  to  the  negro.  But 
perhaps  the  most  characteristic  pygmies  are  found  in 
Africa.  The  little  Bushmen  and  Hottentots  are  low 
types  of  the  Negrito  stock,  and  they  lead  us  to  the  low- 
est men  of  all,  the  Akkas  of  the  West  Congo  region.  It 
is  difficult  for  us  to  realize  how  utterly  degenerate  and 
apelike  these  pygmies  are.  The  jaws  are  dispropor- 
tionately large  as  compared  with  the  cranium  or  brain- 
case,  and  project  to  a  degree  which  brings  the  skull 
very  close  to  that  of  the  higher  apes ;  while  in  mental 
respects,  in  the  absence  of  dwellings,  and  in  many 
other  ways  they  prove  to  be  the  lowest  of  all  mankind, 
—  veritable  brutes  in  form  and  mode  of  life. 


Without  a  full  series  of  photographs  before  us  the 
foregoing  sketch  of  the  various  races  of  men  cannot 
make  us  fully  acquainted  with  all  the  strange  varieties 
of  the  human  body,  but  it  will  suffice  to  establish  two 


EVOLUTION   OF  THE  HOIAN   SPECIES  195 

fundamental  results.  While  all  men  agree  in  the  pos- 
session of  certain  features  which  set  them  apart  from 
other  members  of  the  primate  order,  they  differ  among 
themselves  in  such  a  way  as  to  fall  into  four  well-marked 
subdivisions  branching  out  from  a  common  starting- 
point.  Furthermore,  in  each  of  these  i)rimary  groups 
the  subordinate  types  arrange  themselves  also  in  the 
manner  of  branches  arising  from  a  common  limb. 
This  is  the  relation  that  we  have  earlier  found  to  be  a 
universal  one  throughout  the  animal  kingdom,  and 
science  believes  that  it  indicates  everywhere  an  evolu- 
tionary history  —  an  actual  development  along  dif- 
ferent lines  of  descent  of  forms  w^hich  have  a  common 
starting-point  and  ancestry. 

The  second  principle  is  perhaps  even  more  significant : 
when  we  review  the  many  races  from  the  Caucasian  to 
the  dwarf  Negrito,  we  traverse  a  downward  path  which 
will  bring  us  inevitably  to  the  higher  apes.  In  our 
survey  of  human  races,  we  have  passed  from  the  Cau- 
casian, with  the  largest  brain  and  cranium  and  with 
straight  jaws  w^U  underneath  the  brain-case,  to  the 
pygmy  with  a  relatively  small  brain,  with  huge  pro- 
jecting jaws  and  with  prominent  ridges  over  the  eyes ; 
one  step  more  along  that  path  would  bring  us  to  the 
gorilla  or  the  chimpanzee.  The  array  of  lower  pri- 
mates, from  the  lemur  to  the  gorilla,  gives  a  series  of 
forms  exhibiting  a  progressive  advance  in  respect  to 
the  size  of  the  brain  and  cranium,  and  a  gradual  retreat 
of  the  jaws  to  a  position  underneath  the  cranium  ;  and 
one  step  further  brings  us  to  man.  In  a  word,  these 
two  lines  join  —  in  fact,  they  are  directly  continuous. 
There  is  a  far  smaller  difference  between  the  lowest  man 


196  DOCTRINE  OF  EVOLUTION 

and  the  highest  ape  than  we  have  been  accustomed 
to  suppose. 

Thus  in  general  terms,  it  can  justly  be  said  that 
process  of  evolution  which  developed  the  first  man  from 
its  ape-man  progenitor  seems  to  have  continued  during 
subsequent  ages.  Spreading  out  in  diverging  lines  of 
evolutionary  descent  no  less  clearly  than  they  have  in 
geographical  respects,  certain  races  have  far  surpassed 
their  fellows  of  a  lower  order,  which,  like  the  brute 
P3^gmy,  remain  nearer  the  common  structural  form  from 
which  all  men  have  sprung. 


VI 

THE    MENTAL    EVOLUTION    OF    MAN 

The  problems  dealing  with  the  make-up  of  the  human 
mind  and  with  the  evidences  of  mental  evolution  brins 
the  student  to  matters  of  more  vivid  human  interest. 
Mental  phenomena  are  so  complex  and  intricate  that  it 
is  well-nigh  impossible  to  analyze  their  history  without 
a  knowledge  of  the  principles  derived  from  the  broad 
study  of  evolution  as  a  general  doctrine,  where  human 
prejudice  is  not  so  large  a  factor  and  where  his  perspec- 
tive is  less  affected  by  the  proximity  of  the  observer  to 
his  facts.  For  these  and  other  reasons  the  foregoing 
treatment  of  human  evolution  has  been  confined  to  the 
purely  structural  characteristics  of  man  as  a  species  and 
of  human  races  as  so  many  varieties  of  this  type.  When 
the  broad  comparative  methods  of  biological  science  are 
employed  for  the  elucidation  of  human  anatomical 
facts,  the  result  in  this  special  case,  like  that  established 
through  the  study  of  the  characteristics  of  living  things 
in  general,  is  the  proof  that  evolution  gives  the  most 
rational  and  natural  exphination  of  the  observed  data. 
This  being  true,  the  naturalist  who  turns  from  purely 
structural  matters  to  human  intellect  and  its  history, 
finds  well-tried  methods  of   inquiry  already  available, 

197 


198  DOCTRINE  OF  EVOLUTION 

and  he  approaches  his  further  studies  with  a  conviction 
that  evolution,  having  proved  to  be  universal  so  far, 
in  all  probability  will  be  found  equally  true  in  the  case 
of  psychological  phenomena.  This  expectation  is  in- 
deed realized,  and  the  scope  of  the  doctrine  is  extended 
over  a  new  field,  when  the  facts  of  human  psychology 
are  treated  as  materials  for  impersonal  comparative 
study ;  and  this  result  is  not  only  useful  and  valuable 
in  and  by  itself,  but  it  also  provides  in  the  principles 
of  mental  evolution  the  transition  to  the  field  of  social 
relations  and  ethical  ideas  and  ideals  which  are  appar- 
ently the  unique  possessions  of  men  as  individuals  and 
as  associated  groups. 

The  field  of  comparative  psychology  might  seem  at 
first  sight  to  be  a  foreign  territory  to  the  average  well- 
informed  layman  in  science,  but  the  contrary  is  really 
the  case.  Every  one  has  thought  at  one  time  or  an- 
other about  his  own  mental  make-up,  and  about  the 
minds  of  others.  No  one  can  watch  a  child  at  play 
with  his  toys  or  at  work  with  his  schoolbooks  without 
being  struck  by  many  evidences  of  marked  differences 
between  the  immature  and  the  experienced  types  of 
mind.  Every  one  knows  also  that  the  mental  ''  scheme 
of  things  "  is  by  no  means  the  same  for  all  nations  or 
races  of  mankind  existing  to-day,  while  furthermore 
the  fact  is  entirely  familiar  that  the  intellectual  heritage 
of  a  present  race  has  changed  in  the  course  of  previous 
ages.  Therefore  in  this  field  as  before  we  need  only  to 
amplify  our  knowledge  of  such  representative  psycholog- 
ical facts  as  these  by  drawing  upon  the  full  stores  of 
the  special  investigator,  in  order  to  learn  that  human 
thought,  like  the  human  frame,  has  undergone  a  natural 


MENTAL  EVOLUTION  OF  IVLVN  109 

history  of  transformation  to  become  what  it  is  and  what 
it  was  not. 

Many  who  w^ould  be  ready  to  accept  the  evolution  of 
physical  characteristics  find  it  impossible  to  treat  the 
history  of  human  mentality  as  a  subject  for  dispassion- 
ate consideration,  because  above  all  else  the  intellectual 
powers  of  mankind  seem  to  be  truly  distinctive.  It  is 
only  after  constant  use  of  the  methods  of  science  that 
we  can  bring  ourselves  to  see  how  closely  we  resemble 
lower  forms  in  physical  make-up ;  still  greater  reluc- 
tance must  be  overcome  before  we  can  view  our  mental 
processes  as  counterparts  of  those  of  inferior  animals, 
so  essential  to  our  very  humanity  do  they  seem.  But 
our  duty  to  undertake  the  task  is  plain,  and  its  dis- 
charge will  be  greatly  facilitated  by  a  clear  realization 
that  mental  evolution  is  but  a  part  of  human  transfor- 
mation in  times  past,  as  the  latter  is  only  a  small  frac- 
tion of  the  universal  process  of  organic  evolution  in 
general.  While  our  own  nature  and  inquisitiveness 
give  us  so  intense  an  interest  in  the  teachings  of  science 
that  relate  to  the  constitution  and  history  of  human 
faculty,  wherefore  these  matters  gain  an  undue  promi- 
nence in  perspective,  it  must  never  be  forgotten  that 
these  teachings  do  not  stand  by  themselves,  for  they  are 
built  upon  the  sure  foundations  already  laid  in  physical 
evolution;  and  these  foundations  cannot  be  disturbed 
by  our  failure  to  use  them  as  a  basis  when  we  construct 
our  own  conceptions  of  human  intellect  and  its  history. 


Before  passing  to  the  systematic  review  of  the  facts 
and  principles  of  comparative  psychology  which  demon- 


200  DOCTRINE   OF  EVOLUTION 

strate  evolution,  there  are  certain  general  aspects  of  the 
subject  to  be  considered  so  as  to  clear  the  ground,  as  it 
were,  for  further  progress.  When  the  several  organic  sys- 
tems of  the  human  body  were  compared  with  those  of 
the  apes  and  of  lower  animals,  their  evolution  was  proved 
as  far  as  the  purely  physical  and  material  character- 
istics were  concerned.  But  we  know  that  there  is  no 
part  of  any  one  of  these  systems  which  has  not  its  own 
particular  function,  even  though  this  may  be  a  rela- 
tively passive  one ;  while  furthermore,  science  does 
not  know  of  any  physiological  activity  without  some 
organ  or  tissue  or  cell  as  its  material  basis.  Therefore 
the  evolution  of  an  organic  system  in  material  respects 
involves  its  functional  or  dynamic  evolution  as  an  insep- 
arable correlate ;  the  two  proceed  in  unity,  and  they 
cannot  be  regarded  as  entirely  distinct  without  violat- 
ing common-sense. 

The  fin  of  a  fish  is  used  as  an  organ  of  locomotion  in 
water ;  from  some  such  organ  have  evolved  the  walking 
limbs  of  amphibia  and  reptiles,  constructed  for  pro- 
gression upon  land.  Among  the  mammalia  the  fore 
limbs  have  become  structurally  adapted  so  as  to  be  such 
diverse  organs  of  locomotion  as  the  stilt-like  leg  of  a 
horse,  the  flipper  of  a  seal,  the  whale's  paddle,  and  the 
bat's  wing,  while  among  the  birds  the  wing  may  change 
into  a  flipper  like  that  of  the  penguin,  or  become  reduced 
to  a  vestige  as  in  Apteryx.  We  may  focus  our  attention 
upon  the  material  likenesses  and  differences  in  such  a 
series  of  locomotory  organs,  but  an  inevitable  accom- 
paniment of  their  physical  changes  in  the  transforma- 
tion of  species  has  been  an  evolution  in  the  functional 
matter  of  locomotion.     The   most   complex   and   dif- 


MENTAL  EVOLUTION   OF  MAN  201 

ferentiated  dif^^estive  tracts  of  even  the  highest  animals 
have  evolved  from  a  simple  sac  like  that  of  a  polyp  or 
jellyfish,  as  we  know  from  the  independent  testimony 
of  comparative  anatomy  and  embryology  ;  in  this  ease 
also  the  evolution  of  alimentary  functions  is  no  less 
inseparable  from  the  transformations  in  structural 
respects.  And  again,  we  cannot  understand  the  his- 
torical development  of  vision  without  taking  into 
account  the  eyes  of  various  types  belonging  to  lower 
and  higher  animals. 

So  it  is  with  the  nervous  systems  of  man  and  other 
animals,  and  wdth  their  functions.  The  nervous  system 
of  the  human  organism  comprises  identical  organs  with 
the  same  arrangements  that  are  found  in  other  pri- 
mates and  in  lower  vertebrates  as  well ;  the  differences 
in  structure  are  differences  in  the  degree  of  the  com- 
plexity of  certain  parts,  notably  of  the  cerebrum. 
Therefore  the  evolution  of  human  mentality,  which 
depends  upon  a  human  type  of  brain  as  a  physical  basis, 
is  already  demonstrated  with  the  proof  that  the  human 
brain  and  nervous  system  have  evolved.  It  is  true 
that  an  invariable  and  necessary  connection  between 
mind  and  matter  is  implied  in  the  foregoing  statement, 
and  this  is  something  which  demands  further  consitler- 
ation  at  a  later  point.  But  just  how  the  human  mind 
is  produced  by  or  depends  upon  the  brain,  is  of  far  less 
importance  for  us  at  this  time  than  the  obvious  fact 
that  mental  performance  requires  active  nervous  tis- 
sues. So  far  investigation  has  been  unable  to  discover 
a  valid  reason  for  a  belief  in  the  existence  of  mental 
phenomena,  as  such,  apart  from  some  kind  of  material 
basis.     And  while  we  may  prefer  to  restrict  the  use  of 


202  DOCTRINE  OF  EVOLUTION 

the  word  mind  to  the  series  of  nervous  processes  going 
on  in  the  human  organ  of  thought,  in  so  far  as  these 
processes  are  carried  on  by  the  pecuUar  tissues  of  the 
nervous  system  they  cannot  be  finally  distinguished 
from  the  functional  products  or  accompaniments  of  the 
same  kind  of  active  tissues  and  organs  in  lower  crea- 
tures. Thus  the  subject  of  mental  evolution  becomes 
much  clarified  at  the  outset  by  understanding  that 
nervous  processes  and  nervous  systems  evolve  together. 
In  the  direct  treatment  of  the  facts  and  principles 
of  mental  evolution  we  can  use  exactly  the  same  classi- 
fication and  subdivisions  of  the  materials  of  study  as 
heretofore,  because  psychological  data  are  the  corre- 
lates of  material  organic  systems,  and  also  because  the 
former,  being  natural  phenomena,  are  subject  to  the 
methods  of  analysis  which  can  be  employed  for  any 
series  of  objects  that  have  undergone  evolution.  Sepa- 
rating the  matter  of  fact  from  the  question  as  to  the 
method,  and  recalling  the  main  bodies  of  evidence  as 
to  the  reality  of  evolution,  we  may  establish  four  sec- 
tions of  the  subject  before  us  :  these  are  (1)  the  anatomy, 
(2)  the  embryology,  and  (3)  ''  palaeontology  "  of  mind, 
and  (4)  an  inquiry  into  the  way  nature  deals  with  the 
psychical  characteristics  of  organisms  in  accomplishing 
their  evolution.  To  specify  more  particularly,  it  is 
possible  in  the  first  place  to  compare  the  activities 
belonging  to  the  category  of  mental  and  nervous  opera- 
tions, displayed  by  man  and  other  organisms,  and  the 
results  form  the  subject  of  comparative  descriptive 
psychology;  the  second  division,  namely,  develop- 
mental or  genetic  psychology,  deals  with  the  sequence 
of  events  in  the  life  of  a  single  individual  by  which  the 


MENTAL  EVOLUTION   OF   MAN  203 

infantile  and  adolescent  types  of  mind  become  adult 
intellectuality ;  in  the  third  place,  in  speakiiip;  of  the 
pala3ontology  of  mind,  the  phrase  is  used  to  refer  to  the 
varied  and  changing  mental  abilities  of  human  races  in 
historic  and  prehistoric  times  as  they  may  be  demon- 
strated and  determined  by  the  evidences  of  the  culture 
of  such  earlier  epochs.  In  considering  the  matter  of 
method,  the  questions  are  whether  variation,  inheritance, 
and  selection  are  as  real  in  the  world  of  mental  phe- 
nomena as  they  are  in  the  material  world,  and  whether 
the  laws  are  the  same  or  similar  in  the  two  cases.  We 
shall  learn  how  the  results  of  such  studies  prove  with 
convincing  clearness,  first,  that  the  contents  of  the  indi- 
vidual mind  and  of  the  minds  of  various  human  races 
are  truly  the  products  of  natural  evolution,  and  second, 
that  the  human  mind  differs  only  in  degree  from  that 
of  lower  organisms,  and  not  in  kind  or  fundamental 
nature. 


When  the  operations  of  human  mental  life  are  ex- 
amined, they  include  what  are  called  processes  of 
reason  as  apparently  distinctive  elements.  The  lower 
mammaha  exhibit  a  simpler  order  of  "  mentality  "  de- 
noted intelligence,  while  the  nervous  processes  of  still 
simpler  forms  are  called  instinctive  and  reflex  activities. 
These  are  the  terms  of  the  comparative  array  of  psy- 
chology which  are  to  be  separately  examined  and  classi- 
fied, and  to  be  brought  into  an  evolutionary  sequence 
if  common-sense  directs  us  to  do  so. 

Let  us  begin  our  comparative  study  with  an  example 
of  the  simplest  animals  that  consist  of  only  a  single  cell, 


204  DOCTRINE  OF  EVOLUTION 

such  as  the  Utile  protozoon  Amoeba.  We  have  become 
famiUar  with  this  organism  as  one  that  carries  on  all  of 
the  vital  functions  within  the  limits  of  a  single  struc- 
tural unit ;  it  is  a  mass  of  protoplasm  enclosing  a  nu- 
cleus, and  as  a  biological  individual  it  must  perform  all 
of  the  eight  tasks  that  are  essential  for  life.  It  does 
not  possess  a  digestive  tract,  but  it  does  digest ;  it  does 
not  have  breathing  organs,  but  it  does  respire ;  and  it 
is  particularly  noteworthy  that  it  must  coordinate  the 
different  activities  of  its  parts,  and  maintain  definite 
relations  with  the  environment,  even  though  its  coor- 
dination and  sensation  are  not  accomplished  by  any 
special  parts  that  would  deserve  the  name  of  elementary 
nervous  organs.  Its  many  activities  are  simple  re- 
sponses to  stimuli  that  reach  it  from  without,  and  its 
reactions  to  such  stimuli  are  called  reflex  processes. 
Should  the  light  become  too  strong,  it  will  slowly  crawl 
to  a  shady  place ;  should  the  water  in  which  it  lives 
become  warmer,  it  responds  by  displaying  greater 
activity.  It  exhibits,  in  a  word,  the  property  of  irri- 
tability, —  that  is,  simply  the  power  of  receiving  and 
reacting  to  stimuli ;  and  being  only  a  single  cell  this 
property  is  held  in  common  by  all  of  its  parts. 

We  come  next  to  a  simple  many-celled  animal  like 
the  polyp  Hydra,  or  a  jellyfish.  In  such  an  animal 
the  body  is  composed  of  numerous  cells  which  are  not 
all  alike  either  in  their  make-up  or  in  their  functions. 
Some  of  them  are  concerned  primarily  with  digestion, 
others  with  protection,  while  still  others  are  exempt 
from  these  tasks  and  as  sense-cells  they  devote  all  their 
energies  to  the  reception  of  stimuli  from  without,  or, 
beneath  the  outer  sheet  of  cells  of  the  two-layered  body, 


MENTAL  EVOLUTION   OF  MAN  205 

they  conduct  impulses  from  one  part  of  the  animal 
to  another,  and  thus  serve  as  coordinating  members  of 
the  community.  For  the  first  time,  then,  a  nervous 
system  as  such  is  set  apart  and  specialized  to  devote 
itself  to  the  two  tasks  of  sensation  and  coordination 
that  are  performed  by  nervous  systems  throughout  the 
entire  range  of  organisms  higher  in  the  scale.  But  the 
activities  of  Hydra,  like  those  of  Amoeba,  are  reflex 
and  mechanical,  —  that  is  to  say,  given  similar  stimuli 
and  similar  ^physiological  states  of  the  animal,  the  reac- 
tions ivill  be  the  same.  A  little  water-crustacean  like 
Daphnia  may  swim  against  the  tentacles  of  Hydra; 
it  is  stung  to  death  by  the  minute  cell-batteries  which 
the  animal  possesses,  and  then  in  a  mechanical  way 
the  tentacles  transport  the  food  to  the  mouth,  through 
which  it  is  passed  inward  to  the  digestive  cavity. 
There  is  nothing  that  can  be  called  ''  mentality  " 
throughout  these  processes,  but  the  series  of  activities 
is  much  more  complex  than  in  Amoeba  because  the 
whole  organism  is  constructed  more  elaborately,  and 
because  the  special  and  peculiar  mechanism  directing 
the  activities  has  advanced  to  a  far  higher  condition. 

Passing  to  the  jointed  animals  like  worms  and  in- 
sects, we  find  nervous  mechanisms  that  are  still  more 
intricate,  and  with  their  advance  in  structural  respects 
there  is  a  corresponding  and  correlated  ]:)rogress  in 
their  functions.  Because  the  whole  organism  has  de- 
veloped more  highly  differentiated  groups  of  organs 
to  perform  the  several  biological  tasks,  such  as  eating 
and  respiring  and  moving,  it  is  necessary  for  the  nervous 
structures  concerned  with  the  direction  of  these  actions 
to  become  more  efficient.     An  earthworm  avoids  the 


206  DOCTRINE  OF  EVOLUTION 

light  of  day  and  digs  its  burrow  and  seeks  its  food  by 
wonderfully  coordinated  activities  of  its  muscles  and 
other  parts,  which  are  controlled  by  a  double  chain  of 
ganglia  along  its  ventral  side,  connected  with  a  similar 
pair  of  grouped  nerve-cells  above  the  anterior  part  of 
the  digestive  tract.  The  ganglia  of  each  segment 
exercise  immediate  supervision  over  the  structures  of 
their  respective  territory,  while  they  pass  on  impulses 
to  other  ganglia  so  that  movements  involving  many 
segments  can  be  properly  adjusted.  Everything  an 
earthworm  does  is  controlled  by  the  cells  grouped  in 
these  ganglia,  or  scattered  along  the  intervening  con- 
necting cords.  We  speak  of  its  acts  as  instinctive, 
employing  a  term  which  seems  to  indicate  a  different 
kind  of  operation  carried  on  by  the  nervous  system, 
but  a  moment's  thought  will  show  that  an  instinctive 
act  is  simply  a  complex  group  of  reflex  acts.  The 
physical  basis  and  ultimate  unit  is  a  cell,  and  the  func- 
tional unit  is  likewise  a  cell  act ;  therefore  the  seeming 
difference  proves  to  be  one  merely  of  degree  and  not  of 
kind.  The  greater  complexity  of  the  worm's  nervous 
system  as  compared  with  that  of  Hydra  gives  to  the 
whole  mechanism  a  plasticity  that  diverts  the  attention 
from  the  mechanical  nature  of  the  entire  instinctive 
act  and  of  its  basic  cell  elements. 

The  instinct,  like  the  elementary  reflex,  is  determined 
by  heredity.  Because  a  certain  configuration  of  the 
cells  and  fibers  making  up  a  nervous  system  is  inherited 
as  well  as  the  characters  of  the  constituent  elements 
themselves,  a  worm  or  an  insect  is  enabled  to  act  as  it 
does.  A  butterfly  does  not  have  to  learn  how  to  fly, 
for  it  flies  instinctively.     When  it  emerges  from  its 


MENTAL  EVOLUTION   OF   MAN  %)1 

chrysalis  with  its  complete  adult  series  of  wings  and 
muscles,  it  has  also  the  nervous  mechanism  by  whicli 
these  parts  are  mechanically  controlled.  A  ground- 
wasp  deposits  its  eggs  in  a  small  burrow  in  which  it 
places  also  a  caterpillar  or  a  grasshopper  paralyzed  by 
stinging,  so  that  when  the  larva  is  hatched  from  an  egg 
it  finds  an  ample  supply  of  fresh  food  provided  by  a 
complex  series  of  its  another's  acts  that  seem  to  be 
directed  by  conscious  maternal  solicitude,  ^\^lcn  the 
larva  passes  through  the  later  stages  of  development 
and  makes  its  way  to  the  open  air  as  a  fully  formed 
adult,  it  in  its  turn  may  go  through  the  same  course  of 
action  as  its  parent,  but  it  is  clear  that  it  cannot  have 
any  remembrance  of  its  mother's  work  or  any  personal 
knowledge  of  the  value  of  burying  its  own  eggs  in  a 
chamber  with  a  living  prisoner  to  serve  as  food.  It 
was  an  egg  when  its  parent  did  these  things  ;  as  a  parent 
itself  it  does  not  remain  on  watch  to  see  how  beneficial 
or  fruitless  its  acts  may  be.  A  mechanism  produced 
by  nature's  methods,  the  ground-wasp  behaves  as  it  is 
capable  of  working  with  its  inherited  structure  and  its 
inherited  instinctive  powers  of  coordination  and  sensa- 
tion. 

The  complex  lives  of  communal  insects  like  ants  and 
bees  bring  us  to  the  level  of  mentality  where  an  under- 
standing of  causes  and  effects  seems  to  be  the  guide 
for  conduct.  Nevertheless  the  facts  do  not  warrant 
the  assumption  that  reason  and  intelligence  i)lay  any 
part  in  the  mental  life  of  these  creatures,  as  they  do  in 
the  lives  of  man  and  the  apes.  Because  we  ourselves 
can  see  the  utility  of  the  definite  and  peculiar  behavior 
of  the  queen  and  the  worker,  there  is  no  logical  necessity 


208  DOCTRINE   OF   EVOLUTION 

for  assuming  an  identical  form  of  knowledge  as  a  pos- 
session of  these  insects.  Many  investigators  have 
dealt  with  these  fascinating  subjects,  and  they  are  al- 
most unanimous  in  the  conclusion  that  the  instinct 
of  an  insect  is  a  mechanical  and  hereditary  synthesis 
of  combined  reflex  acts. 

The  lower  orders  of  psychological  processes  play  a  far 
larger  part  in  the  lives  of  the  higher  animals  than  we  are 
wont  to  believe.  A  pointer  and  sheep  dog  possess 
different  qualifications  in  the  way  of  instincts  that 
make  them  useful  to  man  in  different  ways.  A  bull- 
dog or  a  game-cock  does  not  reason  out  its  course  of 
action  during  a  contest,  but  like  a  mechanism  when 
the  spring  is  released,  it  acts  promptly  and  with  effect. 
A  ball  flashing  past  the  human  eye  causes  the  lids  to 
close  unconsciously,  and  it  is  not  always  possible  to 
inhibit  this  instinctive  mechanical  act  by  the  exercise 
of  the  will.  An  examination  of  the  workings  of  the 
human  body  reveals  manifold  activities  of  an  even  lower 
or  reflex  nature,  like  the  movements  of  the  viscera  and 
the  adjustments  in  respect  to  the  amount  of  supplies 
of  blood  sent  to  different  parts  of  the  body  as  local 
needs  arise.  Directed  always  by  specific  portions  of 
the  nervous  system,  such  reflex  actions  play  their  part 
in  human  life  without  any  effort  on  the  part  of  reason 
and  so-called  will,  and  without  coming  into  conscious- 
ness except  indirectly  and  subsequently. 

Passing  by  many  interesting  members  of  the  psy- 
chological series  of  intergrading  forms,  we  reach  the 
familiar  animals  like  the  cat  and  dog  and  horse  which 
display  what  is  called  intelligence.  This  is  the  power 
to  learn  by  experience,  and  to  improve  the  quality  and 


MENTAL  EVOLUTION  OF  M.VN  209 

promptitude  of  reactions  to  stimuli.  In  certain  re- 
spects intelligence  seems  to  differ  from  instinct,  inas- 
much as  it  involves  a  response  to  stimuli  that  may 
be  altered  and  quickened  by  repeated  exjierience,  but 
in  ultimate  analysis  the  two  forms  of  psychological 
processes  are  fundamentally  alike.  A  single  example 
chosen  from  Thorndike's  extensive  investigation  will 
serve  to  bring  out  the  primary  characteristics  of  intelli- 
gence. A  cat  was  placed  in  a  latticed  cage  provided 
with  a  door  that  could  be  opened  from  within  when  a 
catch  was  pressed  down,  and  meat  was  put  in  a  dish 
outside  the  door  where  the  cat  could  see  it.  At  first, 
the  animal  escaped  from  the  cage  by  freeing  the  door 
during  its  aimless  scrambling  about  the  catch,  but  as 
trial  after  trial  was  made,  the  time  necessary  for  the 
cat  to  make  its  way  out  was  shortened,  until  after 
seventy-five  or  one  hundred  trials,  the  animal  innne- 
diately  opened  the  door  and  seized  the  food.  In  me- 
chanical terms,  the  connection  between  ''  scrambling 
about  the  door  "  and  "  freedom  to  get  the  meat  "  be- 
came established  by  numerous  repetitions  until  the 
originally  disconnected  elements  were  physiologically 
associated  and  made  inseparable.  When  animals  like 
horses  and  seals  and  dogs  are  trained  for  the  circus,  it  is 
by  exactly  the  same  method,  for  training  consists  merely 
in  the  establishment  of  a  psychological  sequence  so  that 
the  performance  of  one  series  of  acts  leads  mechanically 
to  others.  Thus  we  learn  that  the  psychological  prop- 
erty called  intelligence  is  the  ability  to  establish  wide 
relations  between  numerous  activities  which  are  them- 
selves of  a  more  or  less  complex  nature ;  and  we  fintl 
also  that  because  these  elements  are  ultimately  nervo- 


210  DOCTRINE  OF  EVOLUTION 

cell  and  sense-cell  reflexes,  an  intelligent  response  is 
quite  as  machine-like  as  any  and  all  of  its  elements.  A 
difference  in  degree  of  complexity  and  extent  is  the  only 
thing  that  places  intelligence  apart  from  instinct  and 
reflex  action,  for  the  units  are  the  same  in  all  cases,  — 
so  far  as  science  knows. 

The  apes  are  of  the  greatest  value  in  providing  the 
transition  from  the  grade  of  intelligence  to  the  human 
level  where  reason  is  found.  Whether  or  not  a  chim- 
panzee can  reason  at  all  is  less  important  than  the  fact 
that  its  total  '^mental"  powers  are  lower  than  those 
of  man,  and  higher  than  those  of  inferior  mammalia. 
Apes  are  far  more  susceptible  to  training  than  cats  and 
dogs,  because  their  improved  nervous  mechanism  en- 
ables them  to  establish  a  psychological  sequence  with 
greater  facility.  If  we  are  to  judge  by  the  facts  at  hand, 
these  creatures  possess  a  low  order  of  mentality,  like, 
but  by  no  means  equivalent  to,  that  of  man. 

At  the  end  of  the  comparative  scale,  we  reach  the 
human  mind  which  is  characterized  by  its  ability  to 
perceive  and  recognize  far  wider  relations  than  those 
which  are  involved  in  intelligence.  Human  conscious- 
ness is  the  stream  of  thoughts  and  feelings  which  con- 
stitute the  immediate  contents  of  mind.  In  our  own 
case,  we  know  both  the  activities  we  perform  and  some 
of  the  internal  phenomena  with  which  such  activities 
are  connected.  Then  we  are  impelled  to  compare  the 
objective  phenomena  of  action  with  the  behavior  of 
other  men  and  of  lower  organisms,  and  if  their  behavior 
does  not  coincide  with  our  own  we  are  justified  in  believ- 
ing that  its  direction  lacks  some  of  the  elements  we  know 
about  in  our  own  case.     This  is  the  method  of  compar- 


MENTAL  EVOLUTION   OF  MAN  211 

ative  psychology,  which  establishes  the  conclusion  that 
reason  is  the  more  complex  term  of  a  series  to  which 
reflex  action,  instinct,  and  intelligence  directly  lead. 

Were  w^e  to  study  in  detail  the  psychology  of  adult 
human  beings,  we  would  find  only  more  truly  that 
instinct  and  intelligence  play  a  large  part  in  our  every- 
day mental  life,  and  more  certainly  that  even  the  high- 
est reasoning  powers  we  possess  are  only  more  complex 
in  nature  than  the  nervous  processes  of  lower  mammals 
and  invertebrates.  Just  as  the  nervous  systems  ad- 
vance in  physical  or  structural  respects,  so  must  their 
activities  become  more  and  more  complex  until  the 
result  is  human  faculty. 


We  must  now  briefly  consider  what  may  be  called 
the  '^  comparative  anthropology  "  of  mind  which  deals 
with  the  various  degrees  of  mental  ability  displayed  by 
different  human  races;  this  subject  follows  inevitably 
upon  the  comparison  of  the  human  mind  viewed  as  a 
single  type  with  the  psj^chological  processes  of  lower 
animals.  When  we  reviewed  the  diverse  characteristics 
of  human  races  —  the  protrusion  of  the  jaws,  greater 
or  lesser  stature,  and  the  like  —  it  appeared  that  so- 
called  ''  lower "  races  could  be  distinguished  which 
differed  from  the  '^  higher  "  races  in  the  direction  of  the 
apes ;  the  question  immediately  arises  whether  similar 
distinctions  and  relations  are  discoverable  on  the  basis 
of  mental  traits.  But  in  the  present  case  there  are  not 
so  many  well-substantiated  differentia  at  the  disposal 
of  the  student,  and  it  does  not  appear  so  clearly  that 
the  ''  higher  "  races  are  furthest  from  the  lower  pri- 


212  DOCTRINE  OF  EVOLUTION 

mates  and  lower  mammalia  as  regards  their  mental  pro- 
cesses. What  facts  there  are,  however,  prove  to  be 
highly  significant,  and  they  materially  amplify  our 
conception  of  human  faculty  as  a  product  of  evolution. 
The  essential  point  is  that  the  intellectual  attain- 
ments of  various  races  are  by  no  means  the  same.  The 
calculus  is  a  mental  product  of  the  white  race  only; 
gunpowder  and  printing  from  movable  type  were 
independently  invented  by  the  Caucasian  and  Mon- 
golian races ;  but  the  American  Indian  and  the  Negro 
never  originated  them.  Human  faculty,  to  employ 
the  most  general  term  for  all  that  distinguishes  man 
from  the  brutes,  proves  to  be  a  very  varied  thing  when 
we  draw  comparisons  between  and  among  races  with 
independent  lines  of  ancestry  and  heredity  occupying 
widely  separated  areas.  Should  we  analyze  it,  we  find 
it  to  be  composed  of  three  constituents ;  namely,  the 
physical  elements  of  the  brain,  the  degree  to  which  the 
observational  or  perceptual  and  higher  elements  co- 
operate in  building  up  the  conceptions  peculiar  to  the 
type,  and  the  materials  with  which  the  physical  mechan- 
ism deals,  in  the  way  of  environmental,  educational,  and 
social  '^  grist  for  the  mental  mill."  Many  anthropolo- 
gists accord  too  great  an  importance  to  the  third  con- 
stituent of  human  faculty,  I  believe,  and  they  are 
therefore  led  to  deny  that  races  differ  in  mental  respects 
to  so  large  a  degree  as  the  thoroughgoing  evolutionist 
would  contend.  They  hold  that  differences  in  such 
things  as  powers  of  observation  are  due  to  training : 
that,  for  example,  an  American  Indian  or  a  South  Sea 
Islander  sees  certain  things  in  his  environment  more 
quickly  than  a  white  man  only  because  these  are  the 


MENTAL  EVOLUTION   OF  MAN  213 

things  which  the  experiences  of  his  earher  Hfc  have 
accustomed  him  to  look  for  and  to  find.  This  may  be 
granted,  and  it  may  also  be  admitted  that  children  of 
so-called  ''  lower  "  races  can  be  educated  side  by  side 
with  the  youth  of  white  races  without  noticeably  falling 
behind,  up  to  a  certain  point  when,  at  the  age  of  adoles- 
cence, in  the  classic  case  of  the  Australian  natives, 
other  factors  prove  to  be  obstacles  to  further  i)rogress. 
We  must  also  recognize  that  the  character  of  the  en- 
vironment of  a  race  determines  to  a  large  extent  the 
mode  of  life  of  the  people ;  a  forest-dwelling  Indian  of 
the  interior  is  a  hunter  as  well  as  a  warrior,  while  a 
South  Sea  Islander  is  a  navigator  and  a  fisherman. 

But  the  fact  remains  that  the  inhabitants  of  similar 
countries  have  reached  markedly  different  grades  of 
intellectual  and  cultural  life.  Anglo-Saxon  dominance 
must  be  referred  ultimately  to  Anglo-Saxon  heredity 
and  not  to  the  peculiarities  of  the  land.  Although 
adaptation  is  no  less  necessary  for  men  as  individuals 
and  as  social  groups  than  it  is  for  all  other  living  things, 
I  believe  that  it  is  to  diversity  in  constitutional  endow- 
ments, however  these  may  have  arisen,  that  we  must 
attribute  the  superiority  of  some  races  over  others. 
The  question  is  not  whether  a  savage  race  can  or  cannot 
adopt  the  higher  conceptions  of  a  civilized  people ; 
the  fact  is  that  they  have  not  actually  become  civilized 
by  themselves.  Thus,  while  evolution  in  mental  re- 
spects has  not  resulted  in  the  loss  of  plasticity  in  the 
case  of  the  brain  and  the  nervous  system  as  a  whole, 
wherefore  the  activities  of  these  organs  still  remain 
capable  of  individual  and  racial  modifications  that  are 
impossible  in  the  case  of  the  skeleton  and  in  the  color 


214  DOCTRINE  OF  EVOLUTION 

and  shape  of  the  eye,  it  remains  true  that  races  do  differ 
intellectually,  and  that  their  differences  are  marks  of 
a  mental  evolution  quite  as  definite  as  their  physical 
natural  histories  of  change. 


In  my  own  view  the  strongest  and  most  impressive 
evidence  bearing  upon  the  great  problem  before  us  is 
provided  by  the  series  of  transformations  by  which  the 
human  intellect  develops  during  an  individual  life. 
Mind  has  an  embryology  no  less  significant  than  that 
of  the  skull  or  of  any  other  element  of  the  body;  and 
its  investigation  leads  to  the  evolutionary  interpreta- 
tion quite  as  surely  as  the  study  of  the  various  grades 
of  adult  psychology  constituting  the  anatomical  se- 
quence, which  we  have  reviewed  previously.  When  in 
the  earlier  part  of  the  book  we  dealt  with  embryology 
in  general,  we  learned  how  the  changes  v/hich  take  place 
when  an  organism  develops  from  an  egg  demonstrate 
the  actuality  of  true  organic  transformation  without 
the  necessity  of  concluding  or  inferring  that  this  process 
might  occur.  It  is  not  superfluous  to  insist  again  that 
the  essential  fact  in  evolution  is  the  alteration  of  one 
organic  characteristic  into  another  type ;  must  we  not 
recognize  at  the  very  outset  that  mental  transformation 
is  as  real  as  physical  development  ? 

In  the  first  instance  we  might  concern  ourselves  with 
the  physical  basis  of  mind  and  its  history.  In  the 
earliest  stages  of  human  embryology  no  nervous  system 
whatsoever  is  present,  and  it  is  unreasonable  to  suppose 
that  there  is  anything  going  on  which  corresponds  to 
human  thought.     A  little  later  a  cellular  tube  is  estab- 


MENTAL  EVOLUTION   OF  x\L\N  215 

lished  as  a  primitive  nerve  axis,  which  at  first  is  nearly 
uniform  throughout  its  entire  length  and  clisj)lays  no 
differentiation  into  brain  and  spinal  cord.  Before  long 
an  enlargement  of  the  anterior  end  expands  and  de- 
velops into  a  primitive  three-parted  brain.  It  is  not 
yet  a  real  brain,  however,  and  it  is  entirely  incapable 
of  functioning  in  such  a  way  as  to  justify  the  use  of  the 
word  mental  for  the  results  of  its  operations.  We  know 
that  it  is  only  in  the  cerebral  hemisphere  of  the  adult 
brain  that  the  processes  of  true  human  consciousness 
go  on.  But  it  is  not  until  long  after  the  three-parted 
stage  that  the  cerebral  hemispheres  make  their  appear- 
ance; therefore  we  cannot  speak  of  mind  as  present 
wdien  the  cell  and  tissue  basis  of  mind  is  not  present. 
When,  now,  the  cerebral  hemispheres  do  appear,  they 
are  small  bean-shaped  structures  no  larger  relatively 
than  those  of  a  fish.  Later  they  enlarge  so  as  to  attain 
the  relative  size  of  the  cerebral  hemispheres  of  an 
amphibian,  and  still  later  they  are  like  those  of  a 
reptilian  brain.  Continuing  to  enlarge,  they  begin  to 
fold  so  that  the  total  surface  is  increased  without  very 
much  addition  to  their  bulk.  At  this  time  the  cerebral 
hemispheres  of  the  brain  of  the  human  embryo  are  like 
those  of  an  adult  cat  or  dog.  The  process  of  general 
enlargement  and  of  progressive  convolution  are  con- 
tinued, and  stages  are  reached  and  passed  which  corre- 
spond with  the  monkey  and  ape  conditions. 

Nothing  in  human  development  is  more  impressive 
than  the  origin  of  the  cerebrum  and  its  develo])ment 
by  passing  through  successive  stages  which  are  counter- 
parts in  the  main  of  the  adult  brains  of  other  and  lower 
animals.     The  alteration  of  a  tissue-mechanism  con- 


216  DOCTRINE  OF  EVOLUTION 

structed  in  one  way  into  a  tissue-mechanism  of  a  more 
complex  nature,  provides  the  most  conclusive  evidence 
of  the  reahty  of  brain  evolution,  because  the  process  of 
transformation  actually  takes  place. 

But  in  the  present  connection  we  are  more  interested 
in  the  dynamic  or  functional  aspects  of  mental  evolu- 
tion, which  it  must  be  remembered  are  inseparably 
bound  up  with  the  physical  structiu"es  and  their  modi- 
fications. After  a  human  infant  is  born  its  activities 
are  reflex  and  mechanical  like  those  of  the  adult  mem- 
bers of  lower  groups.  As  it  grows  it  performs  instinc- 
tive acts  because  its  inherited  nervous  system  operates 
in  the  purely  mechanical  manner  of  a  lower  mammal's 
nervous  system.  For  tli'ese  reasons  an  eminent  psy- 
chologist has  -said  that  the  mental  ability  of  an  infant 
six  months  old  is  about  that  of  a  well-bred  fox  terrier. 
The  same  infant  at  nine  months  displays  an  intelligence 
of  a  higher  order  equal  to  that  of  a  well-trained  chim- 
panzee ;  it  has  become  what  it  was  not,  and  in  so  far 
it  has  truly  evolved  in  mental  respects.  At  two  years 
of  age  the  child  is  incapable  of  solving  problems  of  the 
calculus,  for  its  reasoning  powers  are  elementary  and 
restricted,  but  these  same  powers  change  and  intensify 
so  as  to  render  the  older  mind  quite  capable  of  grasping 
the  highest  of  human  conceptions  and  ideas.  In  my 
judgment  the  unbroken  transformation  of  a  child's 
mind  that  exhibits  only  instinct  and  inteUigence  into 
an  adult's  mind  with  its  power  of  reasoning,  is  far  more 
conclusive  as  proof  of  mental  evolution  than  the  infer- 
ence drawn  from  the  comparisons  we  have  made  above 
of  the  adult  psychological  phenomena  of  man,  ape,  cat, 
and  fish.     It  is  surely  natm^al  for  such  mental  trans- 


MENTAL  EVOLUTION  OF   MAN  217 

formations  to  take  place,  for  they  do  take  place  in  the 
vast  majority  of  human  beings;  when  tliey  do  not, 
in  cases  where  the  brain  fails  to  mature,  we  speak  of 
unnatural  or  diseased  minds. 


The  third  division  of  our  evidence  relating  to  mental 
evolution  constitutes  what  we  have  called  the  pala}on- 
tology  of  mind.  By  this  term  we  mean  the  study  of 
human  minds  of  the  past  as  we  may  know  them  through 
the  many  varied  relics  and  documents  which  indicate 
their  characters.  It  is  only  too  obvious  to  every  one 
that  human  knowledge  has  advanced  in  the  course 
of  time  and  that  every  department  of  human  thought 
and  mental  activity  has  participated  in  this  progress. 
No  one  would  have  the  temerity  to  assert  that  we  know 
nothing  more  than  our  ancestors  of  5000  or  even  1000 
years  ago.  Our  common-sense  teaches  us  even  before 
the  man  of  science  produces  the  full  body  of  evidence 
at  his  disposal  that  human  faculties  have  evolved. 
With  regard  to  reasoning  powers,  which  form  one  of  the 
four  distinguishing  characteristics  of  the  human  species 
as  contrasted  with  other  animals,  the  case  has  already 
been  reviewed,  and  we  now  turn  to  speech  and  language 
and  other  departments  of  human  mentality.  When 
we  compare  the  attainments  of  present  day  men  with 
the  abilities  and  ideas  of  their  ancestors  we  will  do  for 
mental  phenomena  precisely  what  was  done  when  we 
compared  the  skeletons  of  modern  animals  with  those 
of  creatures  belonging  to  bygone  geological  ages ;  in 
this  reason  is  found  the  justification  for  the  phrase 
employed  in  the  present  connection. 


218  DOCTRINE  OF   EVOLUTION 

Written  history  furnishes  a  wealth  of  material  for 
interpreting  the  mental  conditions  of  ancient  peoples, 
but  beside  documentary  evidence  the  anthropologist 
learns  to  use  inscriptions  of  prehistoric  times,  the  primi- 
tive graphic  representations  on  tombs  and  monuments, 
and  even  the  characteristics  of  crude  implements  like 
axes  and  arrow-heads.  The  layman  finds  it  difficult 
at  first  to  regard  such  relics  as  indications  of  the  mental 
stature  of  the  people  who  made  and  possessed  them; 
but  a  little  thought  will  show  that  a  man  who  used  a 
rough  stone  ax  in  the  time  of  the  ancient  Celts  could 
not  possibly  have  had  a  mind  which  included  the  con- 
ception of  a  finished  iron  tool  or  modern  mechanism. 
So  in  all  departments  of  human  culture,  the  evolution 
of  material  objects  may  be  justly  employed  in  inter- 
preting and  estimating  the  mental  abilities  of  ancient 
peoples. 


Language  is  undoubtedly  the  most  important  single 
intellectual  possession  of  mankind,  for  it  constitutes, 
as  it  were,  the  very  framework  of  social  organization. 
Without  a  ready  means  of  communication  the  myriad 
human  units  who  perform  the  varied  tasks  necessary 
for  the  economic  well-being  of  a  body-politic  would 
be  unable  to  coordinate  their  manifold  activities  with 
success,  and  the  structure  of  civilized  societies  at  least 
would  collapse.  It  needs  no  legend  of  a  Tower  of  Babel 
to  make  this  plain.  So  fundamental  is  this  truth  that 
although  we  may  not  have  recognized  it  explicitly,  we 
unconsciously  form  the  belief  that  speech  and  language 
are  exclusive  properties  of  the  human  species,  and  even 


MENTAL  EVOLUTION   OF  MAN  219 

more  characteristic  of  man  alone  than  the  power  of 
reason  itself.  While  organized  language  is  clearly 
something  that  as  such  we  do  not  share  with  the  lower 
animals,  nevertheless  we  cannot  regard  the  communi- 
cation of  ideas  or  states  of  feeling  by  sound  as  an  exclu- 
sive property  of  mankind.  All  are  familiar  with  the 
difference  between  the  whine  and  the  bark  of  a  dog 
and  with  the  widely  different  feelings  that  are  ex- 
pressed by  these  contrasted  sounds.  And  we  know  too 
that  dogs  can  understand  what  many  of  their  master's 
words  signify,  as  when  a  shepherd  gives  directions  to 
his  collie.  We  could  even  go  further  down  in  the  scale 
and  find  in  the  shrill  chirping  of  the  katydid  at  the 
mating  season  a  still  more  elementary  combination  of 
significant  instinctive  sound  elements.  To  the  com- 
parative student  the  speech  of  man  differs  from  these 
lower  modes  of  communication  only  in  its  greater  com- 
plexity, and  in  its  employment  of  more  numerous  and 
varied  sounds,  —  in  a  word,  only  in  the  higher  degree 
of  its  evolution.  And  it  is  even  more  evident  that  the 
diverse  forms  of  speech  employed  by  various  races 
have  gradually  grown  to  be  what  they  now  are. 

At  the  outset  it  is  well  to  distinguish  between  writ- 
ing, as  the  conventional  mode  of  symbolizing  words, 
and  spoken  language  itself;  the  two  have  been  more 
independent  in  their  evolution  than  we  may  be  wont 
to  believe.  Speech  came  first  in  historical  develop- 
ment, just  as  a  child  now  learns  to  talk  before  it  can 
understand  and  use  printed  or  written  letters.  Further- 
more, many  races  still  exist  who  have  a  well-developed 
form  of  language  without  any  concrete  way  of  record- 
ing it.     It  is  true,  of  course,  that  back  of  the  conven- 


220  DOCTRINE  OF  EVOLUTION 

tions  of  speech  and  writing  are  the  ideas  themselves 
that  find  expression  in  the  one  way  or  the  other,  or 
even  by  the  still  more  primitive  use  of  signs  and  ges- 
tures. But  it  is  not  with  these  ultimate  elements  of 
thought  that  we  are  now  concerned;  our  task  is  to 
learn,  first,  what  evidences  are  discoverable  which  show 
that  the  property  of  human  language  in  general  has 
originated  by  evolution,  and  then,  in  the  second  place, 
to  perceive  how  this  development  proves  an  evolution 
of  one  group  of  ultimate  ideas,  namely,  human  concepts 
of  the  modal  value  of  words  and  symbols  as  expressions 
of  ideas  themselves. 

A  simple  common-sense  treatment  of  obvious  facts 
will  greatly  facilitate  our  progress.  We  know  very  well 
that  the  English  we  speak  to-day  differs  in  many  ways 
from  the  language  of  Elizabethan  times,  and  that  the 
former  is  a  direct  descendant  of  the  other.  The  latter, 
in  turn,  was  a  product  of  Norman  French  and  Anglo- 
Saxon,  —  a  combination  of  certain  elements  of  both, 
but  identical  with  neither  of  its  immediate  parents. 
The  Saxon  tongue  itself  has  a  history  that  leads  back 
to  King  Alfred's  time  and  earlier.  Thus  we  are  already 
aware  of  the  fact  that  our  speech  has  truly  evolved, 
like  the  physical  structure  of  the  men  who  employ  it ; 
and  we  know,  too,  how  readily  new  words  are  adopted 
into  current  English,  like  tabu  from  Polynesia,  or  garage 
from  the  French,  showing  that  language  is  even  now 
in  process  of  evolution. 

The  sounds  that  make  up  spoken  words  can  be 
resolved  into  a  single  element  with  its  modifications; 
this  basic  element  is  the  brute-like  call  or  shout  made 
with  the  mouth  and  throat  opened  wide  —  a  sound  we 


MENTAL  EVOLUTION  OF  MAN  221 

may  have  heard  uttered  by  men  under  the  stress  of 
pain  or  terror.  All  of  the  various  vowels  are  simply 
modifications  of  this  element  by  altering  the  shape  of 
the  mouth  cavity  and  orifice,  while  the  consonants  are 
produced  by  interrupting  the  sound-waves  with  tlie 
palate  or  lips  or  tongue.  Like  the  cell  as  a  unit  of 
structure  throughout  the  organic  world,  this  elemental 
utterance  proves  to  be  the  basic  unit  of  all  human 
languages,  which  vary  so  widely  among  races  of  to-day 
no  less  than  they  have  in  the  history  of  any  single 
people. 

One  of  the  first  steps  in  the  making  of  spoken  words 
was  taken  by  human  beings  when  they  imitated  the 
calls  or  other  sounds  produced  by  living  things,  and 
tacitly  agreed  to  recognize  the  imitation  as  a  syml)ol 
of  the  creature  making  it.  Thus  the  names  for  the 
cuckoo  and  the  crow  in  many  languages  besides  our 
own  are  simply  copies  of  the  calls  uttered  by  these 
birds;  a  Tahitian  calls  a  cat  mimi;  the  name  for  a 
snake  almost  invariably  includes  the  hissing  attributed 
to  that  creature.  After  a  time  words  which  were  at 
first  simply  imitations  and  which  referred  only  to  the 
things  that  made  these  sounds  came  to  refer  to  certain 
qualities  of  the  things  imitated,  so  that  the  naming  of 
other  than  natural  objects,  such  as  qualities,  began, 
leading  ultimately  to  the  use  of  words  for  qualities 
belonging  to  many  and  different  objects  in  the  way  of 
abstractions. 

Much  light  upon  the  evolution  of  language  is  ob- 
tained when  we  treat  the  speech  of  various  races  as 
we  did  the  skeletal  structures  of  cats  and  seals  and 
whales.     When  we  compare  the  Italian,  Spanish,  For- 


222  DOCTRINE  OF  EVOLUTION 

tuguese,  and  French  languages,  they  reveal  the  same 
general  structure  in  thousands  of  their  words,  —  a 
common  basis  which  in  these  cases  is  due  to  their 
derivation  from  the  same  ancestor,  the  Latin  tongue. 
The  Latin  word  for  star  is  stella,  and  the  Italian  word 
of  to-day  is  an  identical  and  unchanged  descendant, 
like  a  persistent  type  of  shark  which  lives  now  in  prac- 
tically the  same  form  as  did  its  ancestor  in  the  coal 
ages.  The  Spanish  word  is  estrella,  a  modified  deriva- 
tive, but  still  one  that  bears  in  its  structure  the  marks 
of  its  Latin  origin;  the  French  word  etoile  is  a  still 
more  altered  product  of  word  evolution.  Even  in  the 
German  stern,  Norse  stjern,  Danish  starn,  and  English 
star  we  may  recognize  mutual  affinities  and  common 
ancestral  structure.  Choosing  illustrations  from  a  dif- 
ferent group,  the  Hebrew  salutation  ^^  Peace  be  with 
you,"  Shalom  lachem,  proves  to  be  a  blood  cousin  of 
the  Arabic  Salaam  alaikum,  indicating  the  common 
ancestry  of  these  diverse  languages.  Among  Polynesian 
peoples  the  Tahitian  calls  a  house  a  fare,  the  Maori  of 
New  Zealand  uses  whare,  while  the  Hawaiian  employs 
the  word  hale,  and  the  Samoan,  fale.  Whenever  we 
classify  and  compare  human  languages,  we  find  similar 
consistent  anatomical  evidences  of  their  relationships 
and  evolution.  We  can  even  discern  counterparts  of 
the  vestigial  structures  like  the  rudimentary  limbs  of 
whales.  In  the  English  word  night  certain  letters  do 
not  function  vocally,  though  in  the  German  counterpart 
Nacht  their  correspondents  still  play  a  part.  In  the 
word  dough  as  correctly  pronounced  the  final  letters 
are  similarly  vestigial,  although  in  the  phonetic  relative 
tough  they  are  still  sounded. 


MENTAL  EVOLUTION  OF  ^LVN  223 

The  evolution  of  the  art  of  writing  appears  with 
equal  clearness  when  we  compare  the  texts  of  modern 
peoples  with  inscriptions  found  on  ancient  temples  and 
monuments  and  tablets.  Even  races  of  the  present 
day  employ  methods  of  communicating  ideas  by  writ- 
ing symbols  that  are  counterparts  of  the  earliest  stages 
in  the  historic  development  of  writing.  An  Eskimo 
describes  the  events  of  a  journey  by  a  series  of  little 
pictures  representing  himself  in  the  act  of  doing  vari- 
ous things.  A  simple  outline  of  a  man  with  one  arm 
pointing  to  the  body  and  the  other  pointing  away  in- 
dicates '^I  go.''  A  circle  denotes  the  island  to  which 
he  goes.  He  sleeps  there  one  night,  and  he  tells  this 
by  drawing  a  figure  with  one  hand  over  the  eyes,  in- 
dicating sleep,  while  the  other  hand  has  one  finger 
upraised  to  specify  a  single  night.  The  next  day  he 
goes  further  and  he  employs  the  first  figure  again.  A 
second  island  is  indicated,  in  this  case  with  a  dot  in  the 
center  of  the  circle  to  show  a  house  in  which  he  sleeps 
two  nights,  as  his  figure  w^ith  closed  eyes  and  two 
fingers  uplifted  shows.  He  hunts  the  walrus,  an  out- 
line of  which  is  given  alongside  of  his  figure  waving  a 
spear  in  one  hand ;  likewise  he  hunts  with  a  bow  and 
arrow,  which  is  demonstrated  by  the  same  method.  A 
rude  drawing  representing  a  boat  with  two  ui:)right 
lines  for  himself  and  another  man  with  paddles  in  their 
hands  gives  a  further  account  of  his  journey,  and  the 
final  figure  is  the  circle  denoting  the  original  island  to 
which  he  returns. 

Pictography,  as  this  method  of  communicating  ideas 
is  called,  is  often  highly  developed  among  the  Ameri- 
can Indians.     For  example,  a  petition  from  a  tribe  of 


224  DOCTRINE  OF  EVOLUTION 

Chippewa  Indians  to  the  President  of  the  United  States 
asking  for  the  possession  of  certain  lakes  near  their 
reservation  is  a  series  of  pictures  of  the  sacred  animals 
or  ^Hotems"  which  represent  the  several  subtribes. 
Lines  run  from  the  hearts  of  the  totem  animals  to  the 
heart  of  the  chief  totem,  while  similar  lines  run  from 
the  eyes  of  the  subsidiary  totems  to  the  eyes  of  the 
chief,  and  these  indicate  that  all  of  the  subtribes  feel 
the  same  way  about  the  matter  and  view  it  alike,  — 
the  sentiment  is  unanimous.  From  the  chief  totem 
run  out  two  lines,  one  going  to  the  picture  of  the  desired 
object,  while  the  other  goes  to  the  President,  conveying 
the  petition.  Thus  pictography,  a  method  of  writing 
that  belongs  to  the  childhood  of  races,  may  be  made 
to  communicate  ideas  of  a  strikingly  complex  nature. 

The  ancient  and  modern  inscriptions  of  Asia,  from 
the  Red  Sea  to  China,  present  many  significant  stages 
in  the  development  of  picture-writing.  In  earliest  ages 
the  men  of  Asia  made  actual  drawings  of  particular 
objects,  such  as  the  sun,  trees,  and  human  figures; 
subsequently  these  became  conventionalized  to  a  cer- 
tain degree,  but  even  as  late  as  3000  B.C.  the  Akkadian 
script  was  still  largely  pictographic.  From  it  origi- 
nated the  knife-point  writing  of  Babylonian  and  Chal- 
dean clay  tablets,  while  among  the  peoples  of  Eastern 
Asia,  who  continued  to  draw  their  symbols,  the  tran- 
sition to  conventionalized  pictures  such  as  those  made 
by  the  Chinaman  was  slower  and  less  drastic. 

In  another  Hne  of  evolution,  the  hieroglyphics  of 
Egyptian  tombs  and  monuments  illustrate  a  most 
interesting  intermediate  condition  of  development. 
These  inscriptions  have  been  deciphered  only  since  the 


MENTAL  EVOLUTION  OF  ALVN  225 

discovery  of  the  famous  Rosetta  stone-fragnicnt,  wliicli 
bears  portions  of  three  identical  texts  written  in  hiero- 
glyphics, in  Greek,  and  in  another  series  'of  symbols. 
The  Egyptian  used  more  or  less  formalized  characters 
to  represent  certain  sounds,  while  in  addition  to  the 
group  of  such  characters  combined  to  make  a  word,  the 
scribe  drew  a  supplementary  picture  of  the  thing  or 
act  signified.  For  instance,  xefiu  means  enemies,  ])ut 
the  Egyptian  graver  added  a  picture  of  a  kneeling  bow- 
man to  avoid  any  possible  misapprehension  as  to  his 
meaning.  The  symbols  denoting  'Ho  walk"  are  fol- 
lowed by  a  pair  of  legs ;  the  setting  sun  is  described 
not  only  by  a  word  but  also  by  its  outline  as  it  lies  on 
the  horizon.  Here  again  one  is  struck  by  the  simi- 
larity between  a  stage  in  the  historic  development  of 
racial  characteristics  and  a  method  employed  at  the 
present  time  to  teach  the  immature  minds  of  children 
that  certain  letters  represent  a  particular  object ;  in  a 
kindergarten  primer  the  sentence  ''see  the  rat  and  the 
cat"  is  accompanied  by  pictures  of  the  animals  specified, 
in  true  hieroglyphic  simplicity. 

Just  as  the  child's  mind  develops  so  that  the  aid  of 
the  picture  can  be  dispensed  with,  and  the  sjmibolic 
characters  can  be  used  in  increasingly  complex  ways, 
in  like  manner  the  minds  of  men  living  in  successive 
centuries  have  evolved.  While  an  evolution  of  human 
conceptual  processes  in  general  is  not  necessarily  im- 
plied by  the  evolution  of  the  forms  of  written  language, 
the  former  process  is  in  part  demonstrated  by  the  latter 
in  so  far  as  the  change  from  the  writing  of  j)ictures  to 
the  use  of  conventional  symbols  involves  an  atlvance 
in  human  ideas  of  the  interpretation  and  vakie  of  the 


226  DOCTRINE  OF  EVOLUTION 

symbols  in  question.  A  man  of  ancient  times  drew  a 
tree  to  represent  his  conception  of  this  object;  in  the 
writing  of  EngUsh  we  now  use  four  letters  to  stand  for 
the  same  object,  and  none  of  these  symbols  is  in  any 
way  a  replica  of  the  tree.  It  is  certainly  obvious  that 
some  change  in  the  mental  association  of  symbol  and 
object  has  been  brought  about,  and  to  this  extent  there 
has  been  mental  evolution. 


Passing  now  to  other  departments  of  human  culture, 
we  must  deal  in  the  next  place  with  the  basic  ^^arts  of 
life";  that  is,  the  modes  of  conducting  the  necessary 
activities  of  every  day.  All  men  of  all  times,  be  they 
civilized  or  savage,  are  impelled  like  the  brutes  by  their 
biological  nature  to  seek  food  and  to  repel  their  foes. 
The  rough  stone  club  and  ax  were  fashioned  by  the 
first  savage  men,  when  diminishing  physical  prowess 
placed  them  at  a  disadvantage  in  the  competition  with 
stronger  animals.  Smoother  and  more  efficient  weapons 
were  made  by  the  hordes  of  their  more  advanced  de- 
scendants, some  of  whom  remained  in  the  mental  and 
cultural  condition  of  the  stone  age  like  the  Fuegian, 
until  the  white  travelers  of  recent  centuries  brought 
them  newer  ideas  and  implements.  In  Europe  and 
elsewhere  the  period  of  stone  gave  place  to  the  bronze 
and  iron  ages,  and  throughout  the  changing  years 
human  inventiveness  improved  the  missile  and  weapon 
to  become  the  bow  and  arrow  of  medieval  civilization 
and  recent  African  savagery.  The  artillery  and  shells 
of  modern  warfare  are  their  still  more  highly  evolved 
descendants. 


MENTAL  EVOLUTION   OF  IVLVN  227 

So  it  is  with  the  dwelHngs  of  men,  and  the  significance 
of  the  changes  displayed  by  such  things.  The  cave 
was  a  natural  shelter  for  i)rimitive  man  as  well  as  for 
the  wolf,  and  it  is  still  used  by  men  to-day.  A\'here  it 
did  not  exist,  a  leafy  screen  of  branches  served  in  its 
stead;  even  now  there  are  human  beings,  like  the 
African  pygmy  and  the  Indian  of  Brazil,  who  are  little 
beyond  the  orang-outang  as  regards  the  character  of 
the  shelter  they  construct  out  of  vegetation.  From 
such  crude  beginnings,  on  a  par  with  the  lairs  and 
nests  of  lower  animals,  have  evolved  the  grass  huts  of 
the  Zulu,  the  bamboo  dwelling  of  the  Malay,  the  igloo 
of  the  Arctic  tribes,  and  the  mud  house  of  the  desert 
Indians.  The  modern  palace  and  apartment  are 
merely  more  complex  and  more  elaborate  in  material 
and  architectural  plan,  when  compared  with  their  primi- 
tive antecedents. 

Baskets,  clay  vessels,  and  other  household  articles 
testify  in  the  same  way  to  an  evolution  of  the  mental 
views  of  the  people  making  them.  The  means  of  trans- 
portation are  even  more  demonstrative.  The  wagon 
of  the  early  Briton  was  like  a  rough  ox-cart  of  the 
present  day,  evolved  from  the  simple  sledge  as  a  begin- 
ning. In  its  turn  it  has  served  as  a  prototype  for  all 
the  conveyances  on  wheels  such  as  the  stage-coach  and 
the  modern  Pullman.  The  history  of  locomotives, 
employed  in  the  first  chapter  to  develop  a  clear  con- 
ception of  what  evolution  means,  takes  its  place  here 
as  a  demonstration  of  the  way  human  itlcas  about 
traction  have  themselves  evolved  so  as  to  render  the 
construction  of  such  mechanisms  possible. 

The  primitive  savage  swimming  in  the  sea  found 


228  DOCTRINE  OF  EVOLUTION 

that  a  floating  log  supported  his  weight  as  he  rested 
from  his  efforts.  By  the  strokes  of  his  arms  or  of  a 
club  in  his  hand,  he  could  propel  this  log  in  a  desired 
direction ;  thus  the  dugout  canoe  arose,  to  be  steadied 
by  the  outrigger  as  the  savage  enlarged  his  experience. 
A  cloth  held  aloft  aided  his  progress  down  or  across 
the  wind,  and  it  became  an  integral  element  of  the 
sailing  craft,  which  evolved  through  the  stages  of  the 
galley  and  caravel  to  the  schooner  and  frigate  of 
modern  times.  When  the  steam-engine  was  invented 
and  incorporated  in  the  boat,  a  new  line  of  evolution 
was  initiated,  leading  from  the  '^  Clermont  "  to  the 
^'  Lusitania  "  and  the  battleship. 

The  history  of  clothing  begins  with  the  employment 
of  an  animal's  hide  or  a  branch  of  leaves  to  protect  the 
body  from  the  sun's  heat  or  the  cold  winds.  Other 
early  beginnings  of  the  more  elaborate  decorative 
clothing  are  discerned  by  anthropologists  in  the  scars 
made  upon  the  arms  and  breast  as  in  the  case  of  the 
Australian  black  man,  and  in  the  figured  patterns  of 
tattooing,  so  remarkably  developed  by  the  natives  in 
the  islands  of  the  South  Pacific  Ocean.  A  visit  to  a 
gallery  of  ancient  and  medieval  paintings  clearly  shows 
that  the  conventional  modes  of  clothing  the  human 
body  have  changed  from  century  to  century,  while 
it  is  equally  plain  that  they  alter  even  from  year  to 
year  of  the  present  time,  according  to  the  vagaries  of 
fashion. 


A  brief  review  of  the  '^arts  of  pleasure,"  including 
music  and  sculpture  and  painting,  demonstrates  their 


MENTAL  EVOLUTION   OF  MAN  229 

evolution  also.  The  earliest  cavemen  of  pAiropo  left 
crude  drawings  of  reindeer  and  bears  and  wild  oxen 
scratched  upon  bits  of  ivory  or  ui)on  the  stone  walls  of 
their  shelters ;  the  painting  and  sculpture  of  early  his- 
toric Europe  were  more  advanced,  but  they  were  far 
from  being  what  Greece  and  Rome  produced  in  later 
centuries.  Indeed,  the  evolution  of  Greek  sculpture 
carried  this  higher  art  to  a  point  that  is  generally  con- 
ceded to  be  far  beyond  that  attained  by  even  our 
modern  sculptors,  just  as  flying  reptiles  of  the  Chalk 
Age  developed  wings  and  learned  to  fly  long  before 
birds  and  bats  came  into  existence. 

.  In  the  field  of  music,  the  earliest  stages  can  be  sur- 
mised only  by  a  study  of  the  actual  songs  and  instru- 
ments of  primitive  peoples  now  living  in  wild  places. 
No  doubt  the  song  began  as  a  recitation  by  a  savage 
of  the  events  of  a  battle  or  a  journey  in  which  he  had 
participated.  In  giving  such  a  description  he  lives 
his  battles  again,  and  his  simulated  moods  and  pas- 
sions alter  his  voice  so  that  the  spoken  history  becomes 
a  chant.  From  this  to  the  choral  and  oratorio  is  not 
very  far. 

Musical  instruments  seem  to  have  had  a  multi])le 
origin.  The  ram's  horn  of  the  early  Briton  and  the 
perforated  conch-shell  of  the  South  Sea  Islander  are 
natural  trumpets ;  when  they  were  copied  in  brass  and 
other  metals  they  evolved  rapidly  to  become  the  varied 
wind  instruments  typified  to-day  by  the  cornet  and 
the  tuba.  In  the  same  way  the  reed  of  the  Greek 
shepherd  is  the  ancestor  of  the  flute  and  clarionet. 
Stringed  instruments  like  the  guitar,  zither,  and  violin 
form  another  class  which  begins  with  the  bow  and  its 


230  DOCTRINE  OF  EVOLUTION 

twanging  string.  The  power  of  the  note  was  intensified 
by  holding  a  gourd  against  the  bow  to  serve  as  a  reso- 
nance-chamber. When  the  musician  of  early  times 
enlarged  this  chamber,  moved  it  to  the  end  of  the 
bow,  and  multiplied  the  strings,  he  constructed  the 
cithara  of  antiquity,  —  the  ancestor  of  a  host  of  modern 
types,  from  the  harp  to  the  bass-viol  and  mandolin. 

The  dance  and  the  drama  find  their  beginnings  in 
the  simple  reenactment  of  an  actual  series  of  events. 
Among  Polynesians  of  to-day  the  dances  still  retain  the 
rhythmic  beat  of  the  war-tread  measure,  and  many  of 
the  motions  of  the  arms  are  more  or  less  conventional- 
ized imitations  of  the  act  of  striking  with  a  club,  or 
hurling  a  spear,  and  other  acts.  To  such  elements 
many  other  things  have  been  added,  but  the  fact  re- 
mains that  our  own  formal  dances,  as  well  as  the  sun- 
dance  of  the  Indian  and  the  mad  whirl  of  the  Dervish, 
are  modern  products  which  have  truly  evolved. 


When  we  turn  to  science  and  philosophy  and  other 
intellectual  attainments  of  modern  civilized  peoples,  it 
is  easier  to  see  how  evolution  has  been  accomplished, 
because  we  possess  a  wealth  of  written  literature  which 
explains  the  way  that  human  ideas  have  changed  from 
century  to  century.  In  these  cases  there  can  be  no 
question  that  such  evidences  provide  accurate  instru- 
ments for  estimating  the  mental  abilities  of  the  writers 
who  produced  them.  We  shall  take  up  the  higher 
conceptions  of  mankind  at  a  later  juncture,  so  at  this 
point  we  need  only  to  note  that  even  these  mental 
possessions,  like  household  culture  and  even  the  phys- 


MENTAL  EVOLUTION  OF  MAN  231 

ical  structures  of  a  human  body,  have  elianp;cd  and 
differentiated  to  become  the  widely  different  interpre- 
tations of  the  world  and  supernal  ure  that  are  held  by 
the  civilized,  barbarous,  and  savage  races  of  to-day. 
As  we  look  back  over  the  facts  that  have  been  cited, 
and  as  we  contemplate  the  large  departments  of  knowl- 
edge about  human  psychology,  mental  development, 
and  racial  culture  w^hich  these  few  details  illustrate,  we 
come  to  realize  how  securely  founded  is  the  doctrine 
that  even  the  human  mind  with  all  its  varied  powers 
has  growm  to  be  what  it  is.  Indeed,  it  is  solely  due  to 
his  mental  prowess  that  man  has  attained  a  position 
above  that  of  any  lower  animal.  And  yet  every  hu- 
man organ  and  its  function  can  be  traced  to  something 
in  the  lower  world ;  it  is  a  difference  only  in  degree 
and  not  in  category  that  science  discovers.  The  line 
connecting  civilized  man  w^ith  the  savage  leads  in- 
evitably through  the  ape  to  the  lower  mammalia  pos- 
sessing intelhgence,  and  on  down  to  the  reflex  organic 
mechanisms  which  end  with  the  Amoeba.  It  is  a  long 
distance  from  the  mechanical  activities  of  the  proto- 
zoon  to  the  processes  of  human  thought ;  yet  the  phys- 
ical basis  of  the  latter  is  a  cellular  mechanism  and 
nothing  more,  developed  during  a  single  human  life  in 
company  with  all  other  organs  from  a  one-celled  start- 
ing-point —  the  human  egg. 


The  method  by  which  mental  evolution  has  been 
accomplished  is  likewise  demonstrable,  because  the 
factors  are  identical  with  those  which  bring  about 
specific  transformation  in  physical  respects.     This  is  to 


232  DOCTRINE  OF  EVOLUTION 

be  expected,  for  the  contention  that  the  structures  and 
the  functions  of  the  several  organs  constituting  any 
system  are  inseparable  has  never  been  gainsaid. 

Mental  variation  is  real.  It  needs  no  scientist  to  tell 
us  that  human  beings  differ  in  intellectual  qualifications 
and  attainments,  and  that  no  two  people  are  exactly 
similar  even  though  they  may  be  brothers  or  sisters. 
The  struggle  for  existence  or  competition  on  the  basis 
of  mental  ability  is  equally  real,  and  every  day  we  see 
the  prize  awarded  to  the  more  fit,  while  those  who  lose 
are  crowded  ever  closer  to  the  wall.  As  in  all  other 
fields  of  endeavor,  the  goal  of  success  can  be  attained 
only  by  adaptation,  which  involves  an  adjustment  to 
all  of  the  conditions  of  existence  —  to  social  and  ethical 
as  well  as  to  the  more  expressly  material  biological 
circumstances. 

Heredity  of  mental  qualities  has  also  been  demon- 
strated notably  by  Galton,  Pearson,  Woods,  and  Thorn- 
dike,  who  have  also  shown  that  the  strength  of  inheri- 
tance in  the  case  of  mental  traits  is  approximately  the 
same  as  for  physical  characteristics  like  stature  and  eye- 
color.  Just  as  a  worker-bee  inherits  a  specific  form 
of  nervous  system  which  cooperates  with  the  other 
equally  determined  organic  systems,  wherefore  the 
animal  is  forced  to  perform  ^^instinctively"  its  peculiar 
specialized  tasks,  so  the  mental  capacity  of  a  human 
being  is  largely  determined  by  congenital  factors. 
Upon  these  primarily  depends  his  success  or  failure. 
It  is  quite  true  that  environment  has  a  high  degree  of 
influence,  so  great  indeed  that  some  speak  of  a  ^^  social 
heredity" ;  they  mean  by  this  phrase  that  the  mental 
equipment    of   an   individual   is    determined   by   the 


MENTAL  EVOLUTION  OF  MAN  233 

things  he  finds  about  him,  or  learns  from  others  with- 
out having  to  invent  or  originate  them  himself.  Thus 
a  Zulu  boy  acquires  the  habits  of  a  warrior  and  a 
huntsman  w^hen  he  grows  up  in  his  native  village, 
although  he  would  undoubtedly  develop  (juite  different 
aptitudes  if  he  should  be  taken  as  an  infant  to  a  city 
of  white  men.  Nevertheless  his  mental  machinery  it- 
self would  be  no  less  surely  determined  by  heredity, 
even  though  the  things  with  which  it  dealt  would  be 
provided  by  an  alien  environment. 

Our  present  knowledge  of  the  nature  and  history  of 
human  mentality  enables  us  to  learn  many  lessons  that 
have  a  direct  practical  value,  although  it  is  impossible 
under  the  present  limitations  to  give  them  the  full 
discussion  they  deserve.  Starting  from  the  dictum 
that  physical  inheritance  provides  the  mechanism  of 
intellect,  education  and  training  of  any  kind  prove  to 
be  effective  as  agents  for  developing  hereditary  quali- 
ties or  for  suppressing  undesirable  tendencies.  Just  as 
wdnd-strewn  grains  of  wheat  may  fall  upon  rock  and 
stony  soil  and  loam,  to  grow  well  or  poorl}^  or  not  at 
all  according  to  their  environmental  situations,  so  chil- 
dren with  similar  intellectual  possibilities  would  have 
their  growth  fostered  or  hampered  or  prevented  by 
the  educational  systems  to  which  they  were  subjected. 
But  the  common-sense  of  science  demonstrates  that 
the  mental  qualities  themselves  could  not  be  altered  in 
nature  by  the  circumstances  controlling  their  develop- 
ment any  more  than  the  hereditary  capal)ility  of  the 
wheat  grains  to  produce  wheat  would  be  altered  by 
the  character  of  the  ground  upon  which  they  fell. 
Education  and  training  thus  find  their  sphere  of  use- 


234  DOCTRINE  OF  EVOLUTION 

fulness  is  developing  what  it  is  worth  while  to  bring 
out,  and  inhibiting  the  growth  of  what  is  harmful. 
That  heredity  in  mental  as  well  as  in  physical  aspects 
provides  the  varying  materials  with  which  education 
must  deal  is  a  fundamental  biological  fact  which  is  too 
often  disregarded.  It  would  be  as  futile  for  an  in- 
structor to  attempt  the  task  of  forcing  the  children  in 
a  single  schoolroom  into  the  same  mental  mold,  as  it 
would  be  for  a  gymnasium  master  to  expect  that  by  a 
similar  course  of  exercise  he  could  make  all  of  his  stu- 
dents conform  to  the  same  identical  stature,  the  same 
shape  of  the  skull,  or  the  same  color  of  the  eye  and  hair. 


Before  leaving  the  subject  of  mental  evolution  we 
must  return  to  the  conception  of  inseparable  mind  and 
matter  with  which  the  present  discussion  began.  The 
whole  problem  of  human  mental  evolution  is  solved 
when  we  accept  the  conclusion  that  the  nervous  mech- 
anism and  the  total  series  of  its  functional  operations 
have  evolved  together  in  the  production  of  the  human 
brain  and  human  faculty.  The  case  regarding  the 
physical  organs  rests  solidly  on  the  basis  of  the  evidences 
outlined  in  a  previous  chapter ;  the  special  examina- 
tion of  purely  mental  phenomena  has  likewise  been 
made  in  the  foregoing  sections.  Just  here  we  must 
pause  to  give  further  attention  to  the  invariable  rela- 
tion between  the  human  mind  and  the  human  brain. 

The  personality  of  human  consciousness  consists  of 
the  current  of  thoughts  and  feelings  flowing  continu- 
ously as  one  of  them  rises  for  a  time  to  dominance  only 
to  fade  when  it  leads  to  and  is  replaced  by  another 


MENTiVL  EVOLUTION   OF  MAN  235 

dominant  element  of  thought.  This  current  is  afTected 
by  the  messages  brought  to  the  brain  by  nerves  from 
the  outer  parts  of  the  body  where  he  the  eye  and  ear 
and  other  sense-organs.  In  hke  manner  the  various 
non-nervous  parts  of  the  body  exert  their  influences 
upon  consciousness,  but  the  affective  processes,  as  they 
are  called,  are  not  as  well  understood  as  the  impressions 
passed  inwards  by  the  sense-organs  along  their  nervous 
roadw^ays  to  the  central  organ,  the  brain.  But  the 
brain  is  the  place  where  the  thinking  individual  re- 
sides ;  and  this  is  one  of  the  most  important  teachings 
of  psychology,  for  not  only  does  it  help  us  to  under- 
stand the  evidence  that  human  faculty  has  evolved, 
but  it  also  inevitably  brings  us  to  consider  certain  \ital 
questions  of  metaphysics,  such  as  the  immortahty  of 
the  thinking  individual  after  the  material  person  with 
its  brain  ceases  to  exist.  However,  the  latter  question 
is  something  which  does  not  concern  us  here ;  now  it 
is  most  important  to  reahze  how  completely  mind  is 
connected  with  the  brain. 

Many  of  the  facts  demonstrating  this  connection  are 
matters  of  common  knowledge.  In  deep  and  dream- 
less sleep  the  essential  tissues  of  the  brain  are  inactive, 
and  in  correspondence  with  the  cessation  of  material 
events  the  thinking  individual  actually  ceases  to  exist 
for  a  time.  Any  one  who  has  ever  fainted  is  subse- 
quently aw^are  of  the  break  in  the  current  of  human 
consciousness  when  the  blood  does  not  fully  supj^ly  the 
brain  and  this  organ  ceases  to  function  properly  ;  a 
severe  blow  upon  the  head  likewise  interrupts  the 
normal  physical  processes,  and  at  the  same  time  the 
mind  is  correspondingly  affected.     Again,  a  progressive 


236  DOCTRINE  OF  EVOLUTION 

alteration  of  the  brain  as  the  result  of  diseased  growth 
causes-  the  mind  to  grow  dim  and  incapable.  Some- 
times infants  are  born  which  are  so  deficient  mentally 
as  to  be  idiots,  and  an  examination  of  the  brain  in  such 
a  case  reveals  certain  correlated  defects  in  physical 
organization.  These  and  similar  facts  form  the  basis 
for  the  dictum  that  the  development  and  evolution  of 
the  brain  mean  the  growth  and  evolution  of  human 
intellect. 

The  further  question  as  to  the  nature  of  the  connec- 
tion is  interesting,  but  it  relates  to  matters  of  far  less 
consequence  to  the  natiu'alist  than  the  central  fact  of 
the  invariable  relation  which  does  exist.  Throughout 
the  centuries  many  philosophers  and  naturalists  of 
numerous  peoples  have  endeavored  to  explain  the  con- 
nection in  question  in  ways  that  have  been  largely 
determined  by  the  changing  states  of  knowledge  of 
various  periods,  as  well  as  by  differences  in  individual 
temperament.  Three  general  conceptions  have  been 
developed :  first,  that  the  material  and  mental  phe- 
nomena interact;  second,  that  they  are  parallel;  and 
third,  that  they  are  one. 

According  to  the  first  view,  the  individual  thoughts 
and  feelings  forming  elements  in  the  chain  of  consecu- 
tive consciousness  are  affected  by  the  events  in  the 
material  physiology  of  the  brain  as  a  physical  structure ; 
the  latter  in  turn  react  upon  the  psychical  or  mental 
elements.  Thus  there  would  be  two  complete  series 
of  phenomena,  which  are  interdependent  and  inter- 
acting at  all  times,  although  each  would  be  in  itself  a 
complete  chain  of  elements. 

The  second  interpretation  is  that  the  two  series  of 


MENTAL  EVOLITIOX   OF  MAN  237 

events  —  namely,  the  physical  processes  of  the  brain 
and  the  elements  of  consciousness  —  are  completely 
independent  but  entirely  parallel.  As  one  writer  has 
put  the  case,  it  is  as  though  we  had  two  clocks  whose 
machinery  worked  at  the  same  rate  and  whose  relation- 
ships were  such  that  ^'one  clock  would  give  the  proper 
number  of  strokes  when  the  hands  of  the  other  pointed 
to  the  hour."  But  in  my  opinion  this  attempted  ex- 
planation of  the  relation  of  mind  to  matter  evades  the 
whole  question,  as  it  does  not  account  for  the  depend- 
ence of  the  former  upon  the  latter,  but  merely  assumes 
the  existence  of  a  more  ultimate  and  unknown  group 
of  causes  for  a  parallelism  in  the  rates  of  operation  of 
two  series  of  things  regarded  as  disconnected. 

The  third  conception  recommends  itself  to  many  on 
account  of  its  greater  simplicity.  Formulated  as  the 
doctrine  of  monism,  it  states  that  the  mind  and  its 
material  basis  are  merely  different  aspects  of  one  and 
the  same  thing,  and  that  there  is  only  one  series  of 
connected  elements  which  are  known  to  us  directly  as 
the  current  of  our  thoughts  and  indirectly  as  the  phys- 
iological processes  going  on  mainly  in  the  cerebrum. 
Thus  mind  is  purely  subjective,  the  brain  is  only  me- 
diately objective.  It  is  because  the  mental  and  the 
material  are  so  intimately  related  that  the  monist 
believes  them  to  be  connected  as  are  the  lungs  and 
respiration,  the  hand  and  grasping,  or  the  eye  and  the 
reception  of  visual  impressions  from  without. 

But  whichever  one  of  these  explanations  we  choose 
to  adopt  as  our  own,  the  basic  fact  of  iirirnary  im- 
portance is  that  there  is  an  invariable  dependence  of 
human  thought  upon  a  brain  comprising  a  highly  de- 


238  DOCTRINE  OF  EVOLUTION 

veloped  cerebrum,  whatever  may  be  the  ultunate  nature 
of  the  way  mental  processes  are  determined  by  physi- 
cal processes,  or  vice  versa.  This  fact  stands  unques- 
tioned and  unassailable ;  human  faculty  and  the  brain 
cannot  be  considered  apart,  even  if  they  may  not 
actually  be  different  aspects  of  the  same  basic  '^  mind- 
stuff,"  as  Clifford  calls  the  ultimate  dual  thing. 

Like  all  of  the  other  organs  of  lesser  importance 
belonging  to  the  nervous  system,  the  brain  is  a  com- 
plex of  tissues  which  in  the  last  analysis  are  groups  of 
cell-bodies  with  their  fibrous  prolongations.  When  these 
cellular  elements  are  in  operation,  mental  processes 
go  on;  the  unit  of  the  mental  process  therefore  is  the 
functioning  of  a  brain-cell.  But  we  know  that  the 
substance  of  a  brain-cell  is  the  wonderful  physical  basis 
of  life  called  protoplasm,  that  demanded  our  attention 
at  the  outset.  The  chemicals  that  go  to  make  up 
protoplasm  are  everywhere  carbon,  hydrogen,  oxygen, 
and  other  substances  that  are  exactly  the  same  out- 
side the  body  as  inside.  It  is  the  combination  of  these 
substances  in  a  peculiar  way  which  makes  protoplasm, 
and  it  is  the  combination  of  their  individual  properties 
which  in  a  real  even  though  unknown  manner  gives 
the  powers  to  protoplasm,  even  to  that  of  a  living  brain- 
cell.  Does  science  teach  us,  then,  that  the  ultimate 
elements  of  human  faculty  are  carbon-ness  and  hydro- 
gen-Tiess,  and  oxygen-ness,  which  in  themselves  are  not 
mind,  but  which  when  they  are  combined,  and  when 
such  chemical  atoms  exist  in  protoplasm,  constitute 
mental  powers?  Plain  common-sense  answers  in  the 
affirmative.  We  need  not,  indeed,  we  must  not,  attrib- 
ute mind  as  such  to  rock  salt  or  to  the  water  of  a 


MENTAL  EVOLUTION   OF  MAN  239 

stream,  but  we  do  know  that  salts  and  water  and  other 
dead  substances  may  enter  into  the  composition  of  the 
material  brain  which  is  the  physical  basis  of  mind. 

In  my  opinion  the  individual  argument  renders  the 
monistic  conception  of  mind  and  matter  unassaihible. 
The  food  that  we  may  eat  and  the  water  we  may  drink 
are  dead,  and  as  such  they  display  absolutely  no  evi- 
dence of  nervous  or  mental  processes.  Wlien  they 
enter  our  bodies,  they  with  other  foods  replcnisli  the 
various  tissues,  and  among  these  the  parts  of  the  brain. 
In  a  material  sense  they  become  actual  living  proto- 
plasm, replacing  the  worn-out  substances  destroyed 
during  our  previous  thinking ;  and  their  properties  are 
combined  to  make  brain  and  thought,  to  play  for  a 
time  their  part  in  life,  and  to  pass  back  into  the  world 
of  dead,  unthinking  things.  Every  one  of  us  knows 
that  hunger  reduces  our  ability  to  tliink  clearly  and 
fully,  and  every  one  knows  also  that  mental  vigor  is 
renewed  when  fresh  supplies  of  nourishment  reach  the 
brain.  What  can  be  the  source  of  mentality,  if  it  is 
not  something  brought  in  from  the  outer  world  along 
with  the  chemical  substances  which  taken  singly  are 
devoid  of  mind  ?  Scientific  monism  frankly  replies 
that  it  is  unable  to  find  another  origin. 

We  are  thus  brought  to  recognize,  not  only  the 
continuity  taught  by  organic  evolution,  but  also  the 
uniformity  of  the  materials  constituting  the  entire 
sensible  world,  inasmuch  as  the  ultimate  unit  of  all 
nervous  phenomena  is  the  reflex  act  of  a  protoplasmic 
mass,  which  itself  is  a  synthesis  of  properties  inhering 
in  the  chemical  elements  making  up  living  matter. 
Among  inorganic  things  the  mind-stuff  units  are  com- 


240 


DOCTRINE   OF  EVOLUTION 


bined  in  relatively  simple  ways,  and  the  ^' stuff  does 
not  give  any  outward  evidences  of  '^mind"  as  such. 
Living  things  are  almost  infinitely  complex  as  regards 
their  chemical  organization,  and  even  in  the  very  lowest 
of  them  we  can  discern  a  cell-reflex  element  which, 
combined  with  others  like  it,  forms  the  unit  of  the 
compounds  we  call  instinct,  intelligence,  and  reason. 
Hence  through  an  analysis  of  mental  evolution  we  are 
enabled  to  form  the  larger  conception  of  a  continuous 
universe  whose  ultimate  elements  are  the  same  every- 
where. 


VII 

SOCIAL   EVOLUTION   AS   A   BIOLOGICAL   PROCESS 

We  now  reach  a  critical  juncture  in  our  study  of  the 
foundations  of  evolutionary  doctrine,  for  we  must  pass 
at  this  point  to  an  inquiry  into  the  nature  and  origin 
of  human  social  relations.  In  undertaking  this  task 
we  may  seem  to  leave  the  field  which  is  properly  that  of 
organic  evolution,  and  many  perhaps  will  be  unwilling 
to  view  such  aspects  of  human  life  as  materials  for  purely 
biological  analysis,  arrangement,  and  explanation.  But 
even  before  the  reasons  for  doing  so  may  be  made 
apparent,  every  one  must  admit  that  the  subject  of 
mental  evolution,  which  comprises  so  large  a  bulk  of 
details  expressly  social  in  their  character  and  value, 
virtually  compels  us  to  scrutinize  the  history  of  the 
economic  and  other  interrelationships  maintained  by 
the  human  constituents  of  civilized,  barbarous,  and 
savage  communities.  Language  has  been  treated  as  an 
individual  mental  product,  and  so  have  the  arts  of  life 
and  of  pleasure ;  but  all  of  these  things  find  their  great- 
est utility  in  their  social  usage, — in  their  value  as  bonds 
which  hold  together  the  few  or  many  human  beings 
composing  groups  of  lower  or  higher  grade.  Without 
discovering  any  other  reasons  we  would  l)o  impelled  to 
take  up  social  evolution,  for  this  process  is  inextricably 
bound  up  with  the  origin  and  development  of  all  de- 
partments of  human  thought  and  action. 

R  241 


242  DOCTRINE  OF  EVOLUTION 

If  now  this  new  field  is  actually  to  be  included  within 
the  scope  of  the  laws  controlling  the  rest  of  nature's 
evolution,  two  general  conclusions  must  be  established. 
Although  no  formal  order  need  be  followed,  it  must  at 
some  time  be  shown  that  human  social  relations  are 
biological  relations,  to  be  best  explained  only  through 
their  comparison  with  the  far  simpler  modes  of  asso- 
ciation found  by  the  biologist  among  lower  orders  of 
beings;  and  in  the  second  place  it  must  be  demon- 
strated that  identical  biological  laws,  uniform  in  their 
operation  everywhere  in  the  organic  world,  have  con- 
trolled the  origin  and  estabhshment  of  even  the  most 
complex  societies  of  men.  So  far  no  reason  has  been 
discovered  by  science  for  believing  that  evolution  has 
been  discontinuous,  holding  true  only  for  the  merely 
physical  characteristics  of  humanity  as  a  whole;  and 
furthermore,  the  impersonal  student  of  nature  finds 
ample  positive  evidences  showing  that  the  basic  laws  of 
associations  of  whatever  grade  are  exactly  the  same. 
For  these  laws  we  are  to  seek. 

Heretofore  the  doctrine  of  organic  evolution  has 
been  discussed  with  reference  to  the  single  individual 
organism  viewed  as  a  natural  object  whose  history 
and  vital  relations  require  elucidation.  Both  in  the 
general  arguments  of  the  first  few  chapters  and  in  the 
fifth  and  sixth  chapters  dealing  with  the  single  case  of 
the  human  species,  the  proof  has  been  given  that  all  of 
the  structural  and  physiological  characters  of  any  and 
every  organic  type  fall  within  the  scope  of  the  prin- 
ciples of  evolution,  by  which  alone  they  can  be  reason- 
ably interpreted.  It  has  been  unjust  in  a  sense  to 
ignore  completely  the  importance  of  the  organic  rela- 


SOCIAL  EVOLUTION  AS  A  BIOLOGICAL  PROCESS   243 

tions  of  a  social  nature  to  which  we  are  now  to  turn, 
because  no  individual  can  exist  without  having  its  Hfe 
directly  influenced,  not  only  by  other  kinds  of  organisms, 
but  even  more  intimately  by  other  members  of  its  own 
species.  In  a  single  day's  activity  we  who  are  citizens 
of  a  great  metropolis  are  forced  into  contact  with  almost 
countless  other  Hves,  glancing  off  from  one  and  another 
after  influencing  them  to  some  degree,  and  gaining  our- 
selves some  impetus  and  stimulus  from  our  longer  or 
shorter  intercourse  with  each  of  them.  Our  varied 
social  relations  are  so  many  and  obvious  that  it  is  quite 
superfluous  to  specify  them  as  essential  things  in  human 
life.  For  the  very  reason  that  they  are  so  obvious  and 
constitute  so  large  a  part  of  our  daily  life,  we  are  in 
danger  of  conceiving  them  to  be  exclusively  human  ;  we 
unconsciously  regard  them  as  different  from  anything 
to  be  found  elsewhere  and  quite  independent  of  the 
biological  laws  controUing  the  human  unit. 

On  the  contrary,  as  we  trace  the  development  of 
social  organization  from  its  earhest  rudiments  it  be- 
comes ever  clearer  that  evolution  has  been  continuous, 
and  that  during  later  ages  there  has  been  no  suspension 
of  the  natural  laws  w^hich  earher  produced  the  human 
type  of  organism.  The  lessons  we  have  learned  are  by 
no  means  to  be  ignored  from  this  point  forward ;  all  of 
our  conceptions  of  human  biological  history  must  be 
kept  in  mind,  for  anything  new  that  we  may  learn  is 
superadded  to  the  rest,  —  it  cannot  disturb  or  alter 
the  foundations  already  laid.  It  is  even  more  important 
to  reaUze  that  the  same  scientific  method  is  to  be  em- 
ployed which  has  been  so  fruitful  heretofore.  It  has 
given  us  interesting  facts;    it  has  indicated  the  most 


244  DOCTRINE  OF  EVOLUTION 

profitable  lines  of  attack  upon  one  and  another  scien- 
tific problem;  and  it  has  demonstrated  the  practical 
value  of  accurate  knowledge,  even  of  information  about 
the  evolutionary  process.  As  familiarity  with  the  laws 
of  human  physiology  enables  one  to  lead  a  more  hygienic 
and  efficient  life,  and  as  the  results  of  analyzing  the 
evolution  of  mentality  make  it  possible  to  advance 
intellectually  with  greater  sureness,  conserving  our  men- 
tal energies  for  effort  along  lines  established  by  heredi- 
tary endowment,  so  now  we  are  justified  in  expecting 
that  a  clear  insight  into  the  origin  of  our  social  situation 
and  social  obligations  will  have  a  higher  usefulness 
beyond  the  value  of  the  mere  interest  inhering  in  our 
new  knowledge.  Every  one  is  necessarily  concerned 
with  social  questions;  never  before  has  there  been  so 
much  world-wide  discussion  of  topics  in  this  field.  And 
while  it  is  true  that  much  good  may  be  accomplished 
in  utter  ignorance  of  the  past  history  of  human  insti- 
tutions and  of  the  underlying  principles  which  control 
the  varied  types  of  organic  associations,  surely  enlight- 
ened efforts  will  be  more  effective  for  good.  Therefore 
every  member  of  a  community  who  is  capable  of  think- 
ing straight  rests  under  an  obligation  imposed  by  nature 
to  learn  how  he  is  related  to  his  fellow-men  ;  he  must  act 
in  concert  with  them  or  else  he  forfeits  his  rights  as  a 
social  unit.  And  it  is  his  clear  duty  to  search  among 
the  results  of  science  for  aid  in  ascertaining  what  he 
ought  to  do,  and  what  reasons  are  given  by  evolution 
for  the  nature  of  his  vital  duties. 

Despite  the  growing  appreciation  of  the  fundamental 
relation  between  biology  and  sociology,  it  is  still  far 
from  universal.     That  the  latter  science  is  in  a  sense  a 


SOCIAL  EVOLUTION  AS  A  BIOLOGICAL  PROCESS    245 

division  of  the  former  is  more  often  recop:nize(l  by  the 
biologist  than  by  the  average  well-informed  student  of 
human  social  phenomena.  The  layman  in  sociology  too 
often  concerns  himself  solely  with  the  complexities  of 
the  human  problems,  and  he  remains  unaware  of  the 
manifold  products  in  the  way  of  communal  organisms 
far  lower  in  the  scale  of  life  firmly  established  as  primi- 
tive biological  associations  ages  before  the  first  human 
beings  so  advanced  in  mental  stature  that  tribal  unions 
were  found  good.  Among  insects  especially  the,  biolo- 
gist finds  many  types  of  organized  living  things,  rang- 
ing widely  from  the  sohtary  individual  —  a  counterpart 
of  something  even  more  primitive  than  the  most  unsocial 
savage  now  existing  —  up  to  communities  that  rival 
human  civilization,  as  regards  the  concerted  effect  of 
the  diversified  lives  of  the  component  units.  The  stu- 
dent of  the  whole  of  Hving  nature  is  favored  still  more 
in  that  he  learns  how  the  make-up  of  such  a  simple 
organism  as  a  jellyfish  displays  principles  underlying 
the  structure  of  the  whole  and  the  interplay  of  the  parts 
that  are  identical  with  principles  of  organization  every- 
where else.  And  all  of  these  things  can  be  dealt  with 
in  a  purely  impersonal  way  which  is  impossible  when 
attention  is  restricted  to  the  human  case  alone.  Thus  it 
becomes  the  biologist's  privilege  and  his  duty  as  well  to 
place  his  findings  before  those  who  wish  to  understand 
the  constitution  of  human  society  in  order  that  evils  may 
be  lessened  and  benefits  may  be  extended.  He  does  this  so 
far  as  he  may  be  able  in  full  confidence  that  the  elcMuents 
and  basic  principles  are  discoverable  in  lower  nature, 
just  as  they  are  in  the  case  of  the  material  make-up 
and  mental  constitution  of  the  single  human  individual. 


246  DOCTRINE  OF  EVOLUTION 

A  more  explicit  preliminary  statement  must  now  be 
given  of  the  grounds  for  the  belief  that  social  evolution 
is  but  a  part  of  organic  evolution  in  general.  Some  of 
these  reasons  are  not  far  to  seek,  but  their  cogency  can 
scarcely  be  appreciated  until  we  have  examined  the 
concrete  facts  of  the  whole  biological  series.  Any 
human  society  selected  for  examination  —  be  it  a 
tribe,  a  village  community,  or  a  nation — is  in  last  analy- 
sis an  aggregate  of  human  units  and  nothing  besides. 
Its  life  consists  of  the  combined  activities  of  such  com- 
ponents —  and  nothing  else.  Could  we  subtract  the 
members  one  by  one,  there  would  be  no  intangible 
residuum  after  all  the  people  and  their  lives  had  been 
taken  away.  When  these  simple  facts  are  recognized, 
it  is  clear  at  once  that  the  concerted  activities  performed 
by  biological  units  cannot  be  anything  but  organic 
in  their  ultimate  basis  and  nature ;  the  evolution  of 
such  activities  thus  takes  its  place  as  a  part  of  organic 
evolution. 

The  task  of  tracing  out  the  history  of  social  organi- 
zations of  whatever  grade  can  now  be  defined  in  precise 
terms  :  in  simple  words,  it  is  to  learn  how  the  activities 
of  the  component  biological  units  making  up  any  asso- 
ciation really  differ  from  the  vital  performances  of 
biological  units  existing  by  themselves.  What  is  it 
that  distinguishes  a  savage  of  antiquity  from  an  Ameri- 
can of  to-day?  The  modern  example  is  just  as  much 
an  animal  as  the  earlier  type,  and  his  physiology  is 
essentially  the  same.  It  is  something  added  to  the 
common  biological  qualities  of  all  men,  some  relation 
which  does  not  appear  as  such  in  the  life  of  rude  tribes, 
that  makes  the  distinction.     And  it  is  just  this  super- 


SOCIAL  EVOLUTION  AS  A  BIOLOGICAL  PROCESS    247 

added  relation  that  requires  explanation,  an  regards  its 
exact  biological  value  and  its  historic  develoj^mont  a.swcll. 
In  undertaking  this  diflicult  task,  it  seems  best  to 
begin  with  the  very  simplest  organisms  that  biology 
knows,  working  upwards  through  the  scale  to  man.  Hy 
this  course  the  most  basic  elements  ot  organization 
can  be  discovered  without  having  to  look  for  thom 
among  the  intricate  details  of  our  own  vital  situation, 
where  secondary  and  adventitious  elements  stand  out 
in  undue  prominence,  and  where  the  impersonal  vi(nv 
is  well-nigh  impossible.  Step  by  step  we  will  then  work 
up  the  scale  of  social  morphology,  approaching  in  the 
natural  evolutionary  order  that  part  of  the  subject 
which  interests  us  most  deeply. 


Just  as  the  construction  of  an  edifice  must  begin  with 
the  fashioning  of  the  individual  brick  and  bolt  and  girder, 
so  the  evolution  of  a  biological  association  begins  with 
the  unitary  organisms  consisting  of  single  cells,  like 
Amoeba.  We  have  had  occasion  to  discuss  this  animal 
many  times  in  our  previous  studies  of  one  or  another 
aspect  of  evolution,  and  once  again  we  must  return  to 
it  in  order  to  reestablish  certain  points  that  are  of 
fundamental  importance  for  our  present  purposes. 
Within  the  limits  of  its  simple  body,  Ainoeba  performs 
the  several  tasks  which  nature  demands  a  living  thing 
shall  do;  it  feeds  and  respires  and  moves,  continually 
utihzing  matter  and  energy  obtained  from  the  environ- 
ment for  the  reconstruction  of  its  substance  and  replen- 
ishment of  its  vital  powers  ;  it  coordinates  the  activities 
of  its  simple  body,  and  by  its  reflex  responses  to  en- 


248  DOCTRINE  OF  EVOLUTION 

vironmental  influences  it  maintains  its  adjustment  to 
the  external  conditions  of  life.  The  animal  does  all  of 
these  things  with  a  purely  individual  benefit,  namely, 
the  prolongation  of  its  own  life.  While  it  is  performing 
these  individual  tasks,  it  does  not  concern  itself  with 
anything  else  but  its  own  welfare ;  the  interests  of  other 
living  things  are  not  involved  in  any  way,  excepting  in 
the  case  of  other  organisms  that  may  serve  the  animal  as 
food.  Amoeba,  like  every  other  living  thing,  if  it  is  to 
exist,  must  unconsciously  obey  the  first  great  command- 
ment of  nature,  —  ^'Preserve  thyself  J' 

But  its  life  is  incomplete  if  it  stops  with  the  further- 
ance of  aims  that  we  may  call  purely  selfish.  Nature 
also  demands  that  an  Amoeba,  again  like  every  other 
living  thing,  shall  perpetuate  its  kind.  The  mode  by 
which  it  reproduces  is  ordinarily  quite  simple;  the 
animal  grows  to  a  certain  bulk  and  then  it  divides  into 
two  masses  of  protoplasm,  each  of  which  receives  a 
portion  of  the  mother  nucleus.  Sometimes  by  a  peculiar 
process  it  breaks  up  into  numerous  small  fragments 
called  spores,  which  also  receive  portions  of  the  parent 
nucleus.  The  most  striking  feature  in  both  kinds  of 
reproduction  in  Amoeba  is  the  complete  destruction  of 
the  individual  parent  that  exists  before  the  act  and  does 
not  afterwards.  It  is  quite  true  that  every  part  of 
the  mother  animal  passes  over  into  one  or  another  of  its 
products,  but  it  is  equally  true  that  no  one  of  these 
products  is  by  itself  the  original  individual.  So  even 
the  simplest  animal  we  know  performs  a  task  that  is  not 
only  useless  to  itself,  but  is  completely  destructive 
of  itself,  for  nature's  greater  purpose  of  preserving 
the  race.     We  can  readily  see  why  this  must  be  so; 


SOCIAL  EVOLUTION  AS  A  BIOLOGICAL  PROCESS    249 

there  is  no  place  in  the  world  for  a  species  whose  members 
put  individual  well-being  above  the  welfare  of  the  race, 
for  which  the  production  of  new  generations  is  essential, 
even  though  the  satisfaction  of  this  demand  sliould 
necessitate  the  sacrifice  of  the  parent  organism.  We 
might  hesitate  to  use  the  word  ''altruistic"  in  describ- 
ing the  self-destructive  reproductive  act  of  an  Arjiocba, 
because  this  word  connotes  some  degree  of  conscious- 
ness of  the  existence  of  other  than  personal  interests, 
and  of  the  welfare  of  different  individuals.  There  is 
no  reason  to  believe  that  such  conscious  recognition  of 
any  natural  duties  is  possible  in  the  case  of  so  low  an 
organism.  But  the  fact  remains  that  the  result  worked 
out  by  nature  is  the  same  as  though  there  were  a  definite 
understanding  of  real  duties.  Even  this  unitary  or- 
ganism, then,  acts  mechanically  so  as  to  fulfil  two  primal 
obligations,  first  to  itself,  through  activities  with  indi- 
vidual benefit  as  the  result,  and  to  the  race  by  the  act  of 
reproduction  which  closes  its  individual  existence  and 
inaugurates  a  new  generation. 

The  life  of  this  example,  representing  the  whole  series 
of  one-celled  organisms,  is  almost  infinitely  simpler 
than  that  of  a  member  of  a  human  community,  yet  it 
reveals  the  beginnings  of  certain  characteristics  of  the 
latter.  Here,  it  is  true,  the  natural  obligations  in  ques- 
tion are  not  like  those  which  are  ordinarily  denoted 
social,  but  it  is  equally  true  that  even  in  this  most 
elementary  instance  a  living  thing  does  not  li\'e  unto 
itself  alone.  It  is  easy  to  see  the  value  to  the  species  as 
a  whole  of  obedience  to  the  second  great  law  "/'/<- 
serve  thy  kind.''  But  a  httle  further  thought  makes  it 
plain  that  even  the  performance  of  acts  in  compliance 


250  DOCTRINE  OF  EVOLUTION 

with  the  first  mandate  —  '^preserve  thy  self  ^^  —  are  not 
purely  selfish,  although  their  immediate  value  is  realized 
as  individual  benefit.  Surely  an  organism  that  failed 
to  live  an  efficient  individual  hfe  would  be  ineffective 
in  reproduction,  so  that  from  one  point  of  view  every- 
thing an  animal  does  is  tributary  to  the  culminating 
act  performed  for  the  larger  good  of  the  hfe  of  the  whole 
species.  It  is  a  nice  balance  that  nature  has  worked 
out  in  Amoeba,  as  well  as  in  all  other  cases,  between  the 
personal  life  of  the  individual,  complete  only  when  the 
final  process  of  multiplication  supervenes,  and  this 
process  itself,  which  demands  an  efficient  performance, 
even  though  this  is  destructive  of  the  performer. 

Before  passing  to  the  next  members  of  the  series,  which 
reveal  additional  principles  more  truly  social  in  the 
human  sense,  let  us  pause  to  note  that  already  we  have 
found  certain  natural  criteria  that  belong  in  the  depart- 
ment of  ethics.  Even  in  the  case  of  the  biological  unit 
like  Amceba,  which  is  entirely  solitary  and  unrelated  to 
other  individuals  of  its  kind  excepting  in  so  far  as  it  is 
a  link  in  the  chain  of  successive  generations,  any  vital 
activity  can  be  called  good  or  bad,  right  or  wrong. 
Nature  judges  an  act  good  and  right  if  it  tends  to  pre- 
serve the  animal  and  the  species ;  an  act  is  wrong  and 
evil  if  it  is  biologically  destructive  of  the  animal  or  if  it 
interferes  with  the  perpetuation  of  its  kind.  Again 
it  must  be  pointed  out  that  these  terms  are  human  words, 
employed  for  the  complex  conceptions  that  belong  alone 
to  retrospective  and  contemplative  human  conscious- 
ness; to  most  of  us  they  seem  to  imply  the  existence 
of  some  absolute  standard  or  ideal  by  which  a  given 
act  may  be  tested  to  see  if  it  is  right  or  the  opposite. 


SOCIAL  EVOLUTION   AS   A  BIOLOGICAL   PROCESS    251 

If  human  ethics  is  truly  unrelated  to  beginnings  found  in 
lower  nature,  something  that  has  arisen  by  itself  from 
supernature,  then  we  must  not  use  the  terms  in  ques- 
tion except  by  way  of  analogy.  If,  however,  nature  has 
been  continuous  in  the  working  out  of  every  department 
of  human  life  and  human  thought  through  evolution, 
then  the  criteria  of  the  righteousness  of  the  acts  per- 
formed even  by  an  Amoeba  may  be  found  to  be  basic 
and  fundamental  for  ethical  systems  of  whatever  human 
race  or  time.  This  subject  remains  to  be  discussed  in 
the  final  chapter,  but  it  must  be  clear  that  we  cannot 
survey  the  evolutionary  process  by  which  social  sys- 
tems have  come  into  being  without  dealing  at  the  same 
time  with  the  origin  and  growth  of  ethical  conduct  as  such. 


Without  leaving  the  group  of  one-celled  animals 
typified  by  Amoeba,  we  find  colonies  of  the  most  ele- 
mentary biological  nature,  where  other  natural  obliga- 
tions are  added  to  the  two  of  greatest  importance. 
Some  species  of  the  bell-animalcule,  VorliccUa,  provide 
characteristic  examples  of  these  primitive  compound 
protozoa.  Here  the  assemblage  is  made  up  of  one- 
celled  individuals  essentially  similar  to  one  another  in 
structure  and  in  physiological  activities ;  in  the  latter 
respect  each  one  of  them  is  like  Amoeba  as  well.  They 
may  remain  together  for  a  longer  or  shorter  period,  or 
during  their  whole  existence  until  the  time  of  repro- 
duction. Like  the  soHtary  protozoon,  each  moini)er 
leads  a  complete  life  in  and  by  itself,  equivalent  to  that 
of  every  biological  unit.  It  obeys  the  two  great  laws 
already  laid  down,  but  in  addition  it  seems  to  be  rcciuired 


252  DOCTRINE  OF  EVOLUTION 

to  remain  with  the  others  for  some  mutual  good.  The 
biological  value  of  the  association  which  imposes  this 
additional  obligation  may  be  found  perhaps  in  the  fact 
that  a  large  group  is  not  so  readily  eaten  by  an  enemy 
as  an  individual  cell ;  but  it  is  clearer  that  the  process 
of  reproduction,  which  consists  of  the  fusion  of  small 
'^  gametes, "  or  nucleated  fragments  produced  by  diverse 
or  similar  parents,  must  be  greatly  facilitated  by  the 
occurrence  of  gamete-forming  individuals  in  one  and 
the  same  colony.  ^^To  remain  together ^^  is  the  new 
duty  imposed  by  nature  for  the  good  of  all  and  for  the 
welfare  of  each  member  of  the  group.  Some  biological 
advantage  accrues  to  the  several  components,  just  as 
the  banding  of  wolves  enables  the  pack  to  accomplish 
something  which  the  single  wolf  is  unable  to  do,  al- 
though in  the  latter  case  it  is  not  so  much  a  reproductive 
alliance  that  is  formed  as  an  offensive  and  defensive 
union. 

One  step  higher  in  the  scale  stands  the  plant-form 
called  Volvox,  near  the  border-line  betw^een  the  one- 
celled  and  the  many-celled  organisms.  This  aquatic 
type,  about  the  size  of  the  head  of  an  ordinary  pin,  is  a 
hollow  spherical  colony,  with  a  wall  composed  of  closely 
set  cellular  components.  These  elements  are  not  all 
alike,  as  in  the  case  of  colonial  protozoa  like  Vorticella, 
for  they  fall  into  two  classes  which  are  distinguished 
by  certain  structural  and  functional  characteristics. 
Most  of  them  are  simple  feeding  individuals  which 
absorb  nourishment  for  themselves  primarily,  but  they 
pass  on  their  surplus  supplies  to  less  favored  neighbors 
if  occasion  demands.  The  other  members  begin  life 
like  the  first-named,  but  later  they  become  speciahzed 


SOCIAL  EVOLUTION  AS  A  BIOLOGICAL  PROCESS    253 

to  serve  as  reproductive  individuals  solely.  Every 
member  of  the  colony  must  obey  the  first  precept  of 
nature,  otherwise  it  would  be  unable  to  play  its  part  in 
the  hfe  of  the  whole  community.  But  the  discharge  of 
the  second  natural  obligation,  namely  to  preserve  the 
race,  is  here  assigned  to  some,  and  to  some  only,  of  the 
whole  group  of  cell  individuals.  It  follows  therefore 
that  the  division  of  the  tasks  necessary  for  the  mainte- 
nance of  a  complete  biological  individual,  and  the  difTcr- 
entiation  of  the  members  of  the  group  into  two  kinds, 
leads  to  the  establishment  of  an  individuality  of  a 
higher  order  than  the  cell.  Neither  the  purely  nutritive 
nor  the  reproducing  member  is  complete  in  itself; 
the  two  kinds  must  be  combined  to  make  a  perfect 
organism.  The  life  of  any  member  can  be  selfish  no 
longer,  for  if  it  is  to  exist  itself,  it  must  help  others  for 
the  mutual  advantage  of  all.  A  clear  social  relation  is 
thus  established;  and  the  reflex  conduct  of  the  units 
of  a  Volvox  colony  can  be  justly  denoted  altruistic, 
even  though  in  this  case,  as  before,  there  can  be  no  con- 
scious recognition  of  the  reasons  why  mutual  interests 
are  best  served  by  what  is  actually  done. 

One  of  the  most  interesting  and  significant  aspects 
of  the  life-history  of  Volvox  is  the  appearance  for  the 
first  time  of  biological  death.  More  elementary  or- 
ganisms are  immortal  potentially  even  if  not  actually, 
for  every  portion  of  the  body  is  capable  of  passing  over 
into  an  animal  of  a  succeeding  generation.  But  in 
Volvox  a  division  of  labor  has  been  effected  of  such  a 
nature  that  most  of  the  components  discharge  the  tasks 
of  individual  value,  and  with  the  performance  of  these 
they  die.     Only  the  reproductive  members  are  immortal 


254  DOCTRINE  OF  EVOLUTION 

in  the  sense  that  Amoeba  is,  for  they  only  have  a  place 
in  the  chain  of  consecutive  generations  of  Volvox 
colonies.  From  the  standpoint  of  the  nutritive  indi- 
vidual it  is  better  to  be  relieved  of  the  reproductive  task 
in  order  that  there  may  be  no  interruption  of  its  special- 
ized activities  for  the  good  of  all,  but  the  entailed  mor- 
tality is  certainly  disadvantageous  to  it.  It  is  the  higher 
interest  of  the  colony  as  a  whole  that  supersedes  the 
welfare  of  the  parts  taken  singly,  and  this  larger  welfare 
is  safeguarded  by  a  differentiation  worked  out  by  natu- 
ral evolution  which  results  in  the  assignment  of  personal 
and  racial  duties  to  different  individuals,  at  the  cost 
ultimately  of  the  lives  of  the  former. 


We  now  reach  the  realm  of  the  true  many-celled 
animals,  or  Metazoa,  where  the  biological  units  are 
combined  to  form  an  organic  association  displaying  many 
more  resemblances  to  a  human  society.  The  fresh- 
water polyp  Hydra,  like  the  foregoing  illustrations,  is 
one  whose  structure  has  already  been  discussed  in  the 
earlier  chapters,  but  now  we  may  use  it  for  an  analysis 
of  another  series  of  biological  phenomena.  Its  sac-like 
body  consists  of  two  cell-layers ;  the  outer  one  is  con- 
cerned primarily  with  offense  and  defense,  while  the 
inner  layer  is  made  up  of  digesting  or  nutritive  elements. 
The  essential  cells  concerned  solely  with  reproduction 
lie  below  the  outer  sheet.  Comparing  this  animal  with 
an  association  like  Volvox,  we  discover  the  same  differ- 
entiation into  immortal  germ-elements  and  mortal 
cells,  concerned  respectively  with  the  Hydra^s  racial 
existence  and  with  its  individual  life ;  but  far-reaching 


SOCIAL  EVOLUTION  AS  A  BIOLOGICAL  PROCESS    255 

changes  have  come  about  in  the  biological  relationships 
of  the  second  class  of  cells.  In  describing  the  new  phe- 
nomena it  is  absolutely  necessary  to  employ  the  terms 
of  human  social  organization,  because  the  Hydra  s 
body  is  a  true  colony  of  diverse  cells  in  exactly  the  same 
sense  that  a  nation  is  a  body  of  human  beings  with  more 
or  less  dissiinilar  social  functions. 

To  begin  with  the  differentiation  into  ectoderm  and 
endoderm,  the  organism  is  comparable  to  a  human  com- 
munity made  up  of  military  and  agricultural  classes. 
The  cells  of  the  former  group  protect  themselves  and 
the  feeding  elements  also,  w^hile  the  units  of  the  second 
defenseless  type  devote  themselves  to  the  task  of  pro- 
visioning the  w^hole  community,  giving  supplies  of  food 
to  the  defenders  in  exchange  for  the  protection  they 
afford ;  each  kind  needs  the  other,  and  each  performs 
some  distinctive  task  for  the  other  as  well  as  for  itself. 
But  the  parallel  thus  drawm  need  not  stop  here.  In  the 
case  of  the  outer  layer,  the  cells  are  mostly  flat  covering 
elements  that  are  the  first  to  be  torn  off  and  injured 
when  the  animal  is  attacked.  Scattered  about  among 
them  are  sense-cells  standing  like  sentinels  with  deli- 
cate upright  processes  which  receive  stimuli  from  with- 
out ;  the  sense-cells  transmit  impulses  to  the  network  of 
nerve-cells  below,  which  is  a  counterpart  of  the  signal 
corps  of  an  army,  keeping  all  parts  of  the  whole  organi- 
zation in  communication  with  one  another.  Most 
wonderful  of  all  are  the  stinging-cells  of  the  outer  layer ; 
these  produce  a  flask-shaped,  poisoned  bomb  which  is 
discharged  by  the  convulsive  contraction  of  the  cell  it- 
self so  as  to  stun  and  injure  the  enemy  or  prey.  The 
bomb-throwing  cells  die  immediately  after  they  have 


256  DOCTRINE  OF  EVOLUTION 

ejected  their  missiles;  like  soldiers  participating  in  a 
forlorn  hope,  they  sacrifice  their  lives  in  one  supreme 
effort  of  service  to  the  cell-community  of  which  they 
are  members. 

These  and  similar  facts  prove  conclusively  that 
Hydra  is  a  true  community  even  in  the  human  sense, 
and  that  the  laws  of  biological  association  are  estab- 
lished at  a  point  far  below  the  level  of  the  insects.  The 
individuality  of  the  unit  is  still  maintained,  and  each 
cell  must  guard  its  own  interests  to  a  certain  degree, 
but  the  original  independence  of  the  unit  has  become 
so  altered  by  differentiation  and  division  of  labor  that  a 
close  interdependent  relation  has  come  about.  The 
complete  individual  is  now  the  whole  aggregate;  it  is 
the  entire  Hydra  itself  which  must  obey  the  primary 
commands  of  nature  to  live  efficiently  and  to  perpetuate 
its  kind.  True  it  is  that  the  life  of  the  higher  individual 
is  the  sum  total  of  the  activities  performed  by  its  con- 
stituent cells,  but  no  one  of  the  varied  specialized  ele- 
ments is  biologically  perfect  by  itself  or  equivalent  to 
the  whole.  And,  as  we  have  seen,  the  welfare  of  the 
complete  animal  takes  precedence  over  that  of  any  one 
of  its  parts,  just  as  the  existence  of  a  nation  may  be 
preserved  only  by  the  death  of  soldiers  warring  for  its 
honor  and  life. 

If,  now,  we  should  pass  on  to  the  more  complex  or- 
ganisms like  worms  and  insects  and  vertebrates,  and 
should  disregard  the  communal  relations  of  some  of 
these  animals,  each  individual  proves  to  be  like  Hydra 
as  regards  the  principles  underlying  its  make-up  and 
workings.  A  single  bee,  like  a  man,  is  a  definitely  con- 
stituted aggregate  of  cells,  differing  as  a  whole  from 


SOCIAL  EVOLUTION  AS  A  BIOLOGICAL  PROCESS   257 

Hydra  only  in  the  degree  of  differentiation  oxhibited  by 
its  constituent  elements.  Instead  of  a  hjose  network 
of  nerve-cells  there  is  the  far  more  complex  nervous 
system  whose  evolution  has  been  outlined  in  the  sixth 
chapter.  The  blood-vascular  and  respiratory  and  ex- 
cretory systems  have  become  well  organized,  in  response, 
so  to  speak,  to  the  demands  on  the  part  of  the  nervous 
and  alimentary  organs  that  they  may  be  relieved  of  the 
tasks  of  circulation  and  respiration  and  the  discharge 
of  ash-wastes.  Therefore  the  cells  which  make  uj)  an 
insect  and  a  man  are  more  diverse,  they  have  more 
varied  interrelationships,  and  they  are  far  more  inter- 
dependent then  in  the  case  of  the  components  of  Hydra. 
Yet  all  the  many-celled  organisms  that  we  are  so  accus- 
tomed to  regard  as  individuals  are  really  communities, 
demonstrating  the  existence  and  partial  antithesis  of 
the  great  laws  of  egoism  and  altruism,  which  are  trace- 
able even  down  to  Amoeba  and  its  like. 

So  much  has  been  made  of  the  lower  kinds  of  cell- 
associations  because  the  mind  of  the  layman  is  uncon- 
sciously imbued  with  the  idea  that  human  society  is  a 
new  thing,  —  an  idea  which  we  now  see  it  is  necessary 
to  discard  at  the  outset.  Indeed,  the  cell-association 
of  the  Hydra  and  insect  type  is  a  more  compact  and  a 
more  stable  kind  of  community  than  any  grou])  of 
human  individuals  worked  out  by  nature  toward  the 
present  end  of  the  whole  scheme  of  evolution.  That 
is  to  say,  the  subordination  of  cell-interest  to  cell-group 
welfare,  while  it  must  not  go  so  far  as  to  render  the  unit 
incapable  of  doing  its  work,  is  sufhciently  advanced  to 
make  uncontrolled  individualism  impossible.  Let  any 
class  of  Hydra's  cells,  such  as  the  nerve  or  muscle  net- 

B 


258  DOCTRINE  OF  EVOLUTION 

work,  assume  to  exercise  a  selfish  preeminence  or  to 
conduct  a  ^^ strike,"  the  other  classes,  like  the  feeding 
cells,  would  not  be  properly  served  and  they  would  be 
unable  in  consequence  to  work  efficiently  for  the  strikers. 
The  immediate  result  would  be  suicidal,  for  the  selfish 
nerve-class  would  inevitably  suffer  through  the  downfall 
of  the  whole  social  fabric.  It  is  a  nicely  adjusted 
equilibrium  that  is  established,  where  the  ^' equal 
rights"  of  all  the  diverse  cells  consist  in  freedom  to  play 
a  special  part  in  the  life  of  the  group,  serving  other 
individuals  in  return  for  their  service.  The  Golden 
Rule  is  a  natural  law  as  old  as  nature;  for  even  in 
Hydra's  life,  unconscious  discharge  of  duties  to  the  race, 
and  hence  to  others,  is  obligatory.  And  all  these  low 
types  of  organic  associations  evolved  ages  before  the 
rules  of  human  social  order  were  vaguely  recognized 
by  the  reflective  self-consciousness  of  man,  to  be  for- 
mulated as  the  science  of  ethics. 


The  evolution  of  the  wonderfully  varied  societies 
found  among  insects  begins  with  the  solitary  insect 
itself,  just  as  this,  viewed  as  a  cell-community,  origi- 
nates from  one-celled  beginnings  like  Amoeba  through 
progressive  evolution  in  time.  The  similarity  between 
social  insects  and  human  associations  is  clearer  than 
in  the  case  of  a  comparison  between  an  example  from 
either  group  and  a  cell-community,  because  the  higher 
forms  lack  the  organic  contact  of  the  components  which 
is  so  prominent  a  feature  in  the  lower  instance.  The 
social  bonds  are  looser  and  they  allow  a  freer  play  of  the 
constituents ;  but  nevertheless  the  same  laws  that  con- 


SOCIAL  EVOLUTION  AS  A  BIOLOGICAL  PROCESS    259 

trol  the  activities  of  the  cells  making  up  what  we  now 
take  as  the  individual  element,  command  obedience 
on  the  part  of  the  hiterrelated  members  of  an  insect 
community  with  equal  strictness. 

A  butterfly  or  a  moth  is  i)i'iniarily  egoistic  and  unso- 
cial in  the  ordinary  sense  during  its  entire  life-history, 
until  the  final  reproductive  act  which  has  a  value  to  the 
species.  The  caterpillar  larva  devotes  all  of  its  energies 
to  feeding  and  growing,  unconcerned  with  the  fiiKiI 
duties  of  the  moth  with  which  it  is  connected  just  as 
the  indifferent  unit  of  a  young  Volvox  colony  is  related 
to  a  reproducing  member  of  the  full-grown  organism. 
Now  and  then,  it  is  true,  species  like  the  so-called  tent 
caterpillar  are  met  with  where  numerous  larva?  spin 
silken  communal  nests  to  which  they  retire  at  night 
and  in  which  they  remain  to  molt.  The  pupa,  like 
the  larva,  is  individualistic  and  employs  its  time  in 
producing  the  final  adult  form.  The  mature  individual, 
however,  is  constructed  almost  solely  for  the  greater 
purpose  of  perpetuating  the  species.  Indeed  the  larger 
silkw^orm  moths  do  not  and  cannot  feed,  and  their 
value  is  only  that  of  a  device  for  keeping  the  race  estab- 
lished. Adult  may-flies  live  only  a  few  minutes,  j  ust  long 
enough  to  provide  for  the  fertihzation  and  deposition  of 
the  eggs,  although  to  prepare  for  these  acts  the  young 
individuals  must  have  toiled  for  months ;  the  preparatory 
time  may  amount  to  many  years  in  such  a  case  a^?  the 
seventeen-year  locust.  But  nature  is  satisfied,  as  long 
as  the  organic  mechanisms  obey  her  double  command- 
ment, ''Live  and  grow  so  as  to  multiply."  Like  an 
Amoeba,  the  sohtary  insect  must  be  egoistic  at  first,  in 
order  to  be  altruistic  in  a  racial  sense  in  its  last  days. 


260  DOCTRINE  OF  EVOLUTION 

Wasps,  bees,  and  ants  provide  many  familiar  examples 
of  colonial  organizations  that  become  all  the  more  mar- 
velous on  closer  acquaintance,  on  account  of  their 
resemblances  to  human  associations  on  the  one  hand, 
and  to  cell-associations  on  the  other.  Their  illustrative 
beauty  is  enhanced  by  their  wide  variety,  for  they  grade 
from  counterparts  of  highly  civilized  men  down  to  a 
savage  among  insects,  such  as  the  strictly  solitary 
digger-wasp,  whose  instincts  served  to  exemplify  the 
insect  type  of  "mentality"  in  the  discussions  of  the 
preceding  chapter. 

The  true  communities  founded  by  wasps  and  hornets 
must  be  assigned  to  a  low  grade  in  the  scale  because  they 
originate  during  a  single  season  and  break  up  at  its 
end;  for  this  very  reason  the  wasp  community  is  in- 
tensely interesting  to  the  student  of  comparative  social 
evolution.  In  the  spring  a  solitary  female  emerges 
from  the  crevice  where  she  has  hibernated  and  resumes 
active  life ;  she  feeds  for  a  time  to  renew  her  strength 
and  then  she  constructs  a  simple  nest  of  mud  or  masti- 
cated wood-pulp.  In  the  first  few  cells  of  this  nest  she 
deposits  her  eggs,  and  when  they  hatch  she  herself 
provides  the  larvae  with  food,  but  still  continues  to 
enlarge  the  house  and  to  produce  more  eggs.  Thus 
during  the  first  few  weeks  of  the  colony's  existence  this 
single  individual  performs  a  variety  of  tasks  of  racial  as 
well  as  of  purely  egoistic  value ;  but  as  time  goes  on,  a 
profound  change  comes  about  in  her  activities  and  in 
the  life  of  the  whole  community.  The  members  of  the 
first  brood  do  not  grow  into  counterparts  of  their  mother ; 
they  are  all  sexless  "workers"  who  progressively  relieve 
their  parent  of  the  tasks  of  nest-building  and  foraging 


SOCIAL  EVOLUTION  AS  A  BIOLOGICAL  PROCESS    201 

and  nursing,  so  that  their  mother  becomes  a  "queen" 
who  devotes  her  entire  time  to  the  special  reproductive 
task  which  she  only  can  perform.  We  may  justly 
compare  the  queen  to  the  reproductive  organ  of  Hydra, 
for  the  values  to  the  life  of  the  species  are  identical  in 
the  two  cases,  while  the  various  classes  of  workers  are 
counterparts  of  such  units  as  the  muscle  and  nerve  and 
nutritive  components  of  the  Hydra  or  any  other  cell- 
community  individual.  Another  resemblance  between 
the  two  is  found  in  the  death  of  all  the  sexless  individuals 
at  the  end  of  the  season,  when  reproducing  males  and 
females  are  finally  formed,  of  whom  the  fertile  queens 
only  survive  in  their  winter  hiding  places;  and  again 
we  can  discover  the  cause  for  biological  death  in  that 
division  of  labor  which  calls  upon  certain  members  of 
the  whole  community  to  perform  tasks  that  have  no 
value  when  once  provision  has  been  made  for  perpetuat- 
ing the  species.  Finally  the  mode  by  which  the  colony 
grows  and  ampHfies  is  in  all  respects  like  the  embryonic 
development  of  an  egg  into  a  Hydra,  so  that  we  may  add 
the  phrase  ''social  embryology"  to  our  vocabulary.  The 
original  female  is  an  undifferentiated  master  of  all 
trades;  the  small  tribe  she  first  establishes  is  little 
better  off  than  a  horde  of  savages;  but  during  its  sea- 
sonal existence  the  community  increases  in  numbers 
and  complexity  until  it  advances  well  towartl  the  civi- 
lized condition,  when  each  class  performs  its  special 
task  for  the  good  of  all. 

The  bees  take  us  higher  in  the  scale,  although  many 
sohtary  species  occur,  as  well  as  social  forms  lik(^  the 
bumblebees  where  colonies  are  formed  in  a  single 
season  only  to  break  up  with  the  advent  of  cold  weather. 


262  DOCTRINE  OF  EVOLUTION 

The  honeybees,  however,  establish  permanent  com- 
munities from  which  swarms  may  set  out  during  the 
warm  months  to  become  new  colonies  elsewhere.  Many 
hundreds  of  bees  make  up  a  hive,  and  they  belong  to 
three  classes  or  castes,  which  differ  in  structure  and 
social  function.  The  queen  is  a  fertile  female,  the 
drones  are  males,  and  the  workers  are  stunted  and  in- 
fertile females  which  take  no  part  in  reproduction.  In 
this  case  the  queen  never  discharges  any  menial  duties, 
for  these  are  attended  to  by  the  w^orkers ;  she  devotes 
her  entire  time  to  laying  eggs,  which  are  cared  for  by 
her  subjects,  who  act  as  nurses  and  guards  for  the  mon- 
arch as  well.  The  young  workers  serve  at  first  as  door- 
keepers, and  only  later  do  they  take  the  field  in  the 
search  for  nectar  and  pollen,  and  work  as  house-build- 
ers. Each  individual  performs  its  special  task  for  its 
own  benefit  and  for  the  weal  of  all ;  each  possesses  an 
equal  right  to  share  in  the  prosperity  of  the  whole  com- 
munity so  long  as  it  acts  altruistically  as  well  as  egois- 
tically.  And  just  as  the  welfare  of  Hydra  is  superior  to 
that  of  any  one  of  its  constituent  cells,  so  the  well-being 
of  a  hive  of  bees  may  be  safeguarded  only  by  the  actual 
sacrifice  of  some  of  its  members.  Should  food  supplies 
be  inadequate,  the  superfluous  drones  are  stung  to 
death,  —  the  victims  of  legalized  murder.  But  more 
marvelous  still  is  the  provision  that  is  said  to  be  made 
by  certain  individuals  for  their  own  destruction  should 
this  become  desirable.  As  every  one  knows,  a  reigning 
queen  may  leave  the  hive  with  many  of  her  subjects  and 
^' swarm"  in  a  new  locality.  When  she  does  this,  dur- 
ing the  warm  months,  the  workers  of  the  original  hive 
feed  some  of  the  female  larvae  with  richer  food,  and  place 


SOCIAL  EVOLUTION  AS  A  BIOLOGICAL  PROCESS   2G3 

these  potential  queens  or  princesses  in  spooial  roomy 
cells  apart  from  the  ordinary  brood  chambers ;  one  of 
them  soon  emerges  to  become  a  new  sovercip^n.  IM  us 
note  in  passing  how  similar  this  is  to  the  production  of 
new  egg-cells  in  a  Hydra,  when  the  mature  germs  of  an 
earlier  generation  are  prepared  and  discharged.  When, 
now,  the  colder  weather  sets  in,  and  the  possibihty  of 
subsequent  swarming  is  set  aside,  the  reigning  queen  is 
allowed  by  her  attendant  guards  to  visit  the  royal  cells, 
whose  occupants  she  stings  to  death,  thus  destroy- 
ing any  possible  claimant  to  her  place.  And  when  the 
royal  princess  constructs  her  part  of  the  pupal  case, 
she  leaves  an  aperture  so  that  if  and  when  it  should 
become  necessary  for  the  queen  to  kill  her,  the  sovereign 
would  not  injure  her  sting  and  be  unable  to  kill  the  other 
individuals  who  might  become  aspirants  for  the  throne 
and  so  precipitate  a  civil  war  !  As  in  the  case  of  the 
self-destructive  act  on  the  part  of  a  stinging  cell  in 
Hydra,  altruistic  subservience  to  the  interests  of  the 
colony  can  go  no  farther. 

The  ants  form  stable  colonies  of  still  higher  grades, 
where  the  workers  are  not  all  alike  in  general  structure, 
but  become  more  rigidly  specialized  for  the  performance 
of  restricted  tasks.  As  before,  there  is  the  fundamental 
differentiation  into  the  sexual  ''queens"  and  males,  and 
the  sterile  workers  concerned  with  the  immediate 
material  life  of  the  community.  In  some  species  the 
workers  serve  as  herdsmen,  caring  for  the  ant-cattle  or 
aphids,  from  which  they  receive  minute  drops  of  a 
sweet  juice  for  food.  The  aphids  are  tended  on  the 
leaves  of  various  plants  during  tlu^  suninicr,  and  are 
carefully  reared  and  stabled  and  fed  below  ground  during 


264  DOCTRINE  OF  EVOLUTION 

the  winter  months.  In  other  species  seeds  are  procured 
and  stored  in  underground  granaries.  The  leaf-cutters 
are  forms  which  grow  food  suppHes  of  fungi  in  sub- 
terranean mushroom  gardens ;  the  compost  consists  of 
cuttings  brought  from  the  leaves  of  bushes  by  mj^iads 
of  workers,  whose  processions  are  guarded  by  larger- 
headed  soldiers  of  several  ranks.  In  the  honey-ants  of 
Colorado  and  tropical  America  certain  individuals  pass 
their  time  suspended  from  the  roof  of  a  large  nest- 
chamber,  where  they  receive  the  sweet  juice  brought 
in  by  the  workers.  They  serve  as  animated  preserve 
jars,  distended  sometimes  to  the  size  of  a  grape  with  the 
communal  stores  of  food,  which  they  return  to  the 
workers  when  external  sources  of  food  may  fail.  Finally 
there  are  the  slaveholding  species  which  conduct 
forays  upon  the  nests  of  other  forms,  to  procure  the 
young  of  the  latter,  which  grow  up  in  their  captors' 
nests  and  serve  them  as  nurses  and  masons  and  foragers. 
So  long  has  this  custom  been  established  that  some 
slaveholders  are  entirely  unable  to  feed  themselves, 
and  would  die  out  if  their  slaves  failed  to  support  them. 


Let  us  pause  at  this  point  to  summarize  the  results  of 
the  foregoing  analysis,  in  order  that  we  may  approach 
the  biological  study  of  human  associations  with  definite 
and  clear  conceptions  of  the  fundamental  laws  control- 
ling living  communities  of  all  grades. 

We  have  dealt  mainly  with  Amoeba,  Hydra,  and  the 
ant-community  which  exemplify  three  somewhat  dis- 
tinct types  of  organic  individuality.  Some  of  the 
transitional  forms  have  been  specified  to  show  how  the 


SOCIAL  EVOLUTION  AS  A  BIOLOGICAL  PROCESS    265 

second  kind  originates  from  the  first,  and  how  in  its  turn 
this  grows  in  time  into  the  third  and  most  complex 
association;  thus  Vorticella  and  Volvox  connect  Amaba 
with  the  cell-community  individual  like  Hydra  and  a 
sohtary  wasp,  while  the  annually  established  colonies 
of  social  wasps  and  of  bumblebees  lead  to  the  permanent 
colony-individual.  Restricting  attention  to  the  three 
primary  examples,  and  remembering  that  the  criterion 
of  completeness  is  the  ability  to  discharge  satisfactorily 
all  of  the  eight  biological  tasks,  it  is  clear  that  the  entire 
Hydra  and  the  whole  ant-community  correspond  physio- 
logically with  Amoeba,  although  the  first-named  is 
structurally  a  cell-community  equivalent  to  many  pro- 
tozoa, and  the  insect  colony  is  composed  of  many  such 
cell-communities  as  elements.  In  the  third  type, 
neither  a  single  queen  nor  a  single  worker  is  able  to 
carry  on  all  of  the  biological  tasks  any  more  than  a 
muscle-cell  or  an  unformed  egg  of  Hydra  can  maintain 
itself  capably  in  isolation.  Therefore  the  ant-society 
as  a  whole  and  the  Hydra  in  its  entirety  are  organic 
individuals  on  the  same  physiological  plane  with 
Amoeba,  and  they  are  equally  subject  to  the  same  great 
laws  of  nature  demanding  selfish  maintenance  and  ra- 
cial perpetuation. 

But  w-e  must  not  lose  sight  of  the  fundamental  value 
of  the  unit  during  the  evolution  of  a  higher  from  a  lower 
type.  The  tissue-cell  of  Hydra  must  still  obey  the 
mandate  to  live  an  efficient  personal  life,  because  tins 
is  necessary  for  the  welfare  of  other  cells  and  of  the 
w^hole  complex.  The  original  egoistic  tasks  are  not 
abohshed,  but  new  duties  are  added  to  them  in  ways 
we    have    learned    to    distinguish.     In    Vorticella    the 


266  DOCTRINE  OF  EVOLUTION 

products  of  fission  do  not  separate,  and  certain  advan- 
tages accrue  from  the  organic  continuity  thus  main- 
tained. The  success  of  Hydra  in  its  ceaseless  struggle 
to  live  depends  wholly  upon  the  cooperation  of  its 
differentiated  cell-units,  now  no  longer  equivalent  in 
function  to  the  all-powerful  Amoeba,  although  each  one 
must  be  kept  alive  until  its  task  is  done,  or  the  whole 
association  would  have  no  place  in  nature.  Similarly 
in  the  higher  insect  community,  the  superadded  duties 
to  fellow-components  are  even  clearer,  for  in  the  compe- 
tition of  colony  with  colony,  involving  terrific  battles 
whose  casualties  may  be  numbered  by  thousands,  the 
stronger  wins;  and  strength  depends  upon  the  con- 
certed efforts  of  all  the  members  of  the  kingdom,  that 
only  collectively  constitute  a  complete  biological  whole. 
Mere  self -protection  demands  altruistic  conduct :  if 
the  worker  ceased  to  bring  in  food  when  its  own  hunger 
was  satisfied,  there  would  be  no  tribal  stores  for  the 
stay-at-home  queens  and  nurses;  and  if  the  soldier 
fled  from  the  field  of  battle  to  save  its  own  life,  its  act 
would  be  suicidal  ultimately,  for  to  the  degree  of  one 
unit  the  defense  of  its  non-military  supporters  would  be 
weakened  and  they  would  be  so  much  the  less  unpro- 
tected during  their  service  for  the  soldiers  and  all  others. 
Furthermore,  we  must  admit  the  reality  of  natural 
criteria  of  ethical  values,  established  far  below  mankind 
in  the  scale  of  life.  In  an  ant-republic,  laws  are  in- 
stinctively obeyed  quite  as  implicitly  as  though  they 
were  intelligibly  proclaimed  to  all  of  the  emmet  citi- 
zens. Right  is  might  when  community  battles  with 
community,  for  right  is  that  which  is  biologically  favor- 
able.    And  what  may  be  correct  conduct  on  the  part 


SOCIAL  EVOLUTION  AS  A  BIOLOGICAL  PROCESS    2()7 

of  the  members  of  one  species  may  be  naturally  wrong 
and  evil  in  another  case.  To  kill  the  princesses  in  order 
to  obviate  the  possibility  of  civil  war  seein^s  advanta- 
geous and  therefore  right  when  the  (jueen  remains  in 
the  persistent  colony  of  honeybees,  ready  to  do  her  part 
the  following  spring ;  but  it  might  result  in  disiuster  and 
evil  in  the  case  of  the  social  wasps,  whore  the  community 
dies  as  such  in  the  fall,  and  the  continuity  of  the  species 
from  one  year  to  another  requires  the  j)r()du('ti()n  of 
many  queens  lest  the  severe  conditions  of  the  winter's 
hibernation  should  kill  all  fertile  females  if  only  one  or 
two  were  available.  The  standards  of  conduct  are 
simple  indeed ;  and  w'hether  or  not  it  may  seem  best 
to  separate  the  processes  of  social  and  ethical  evolution 
culminating  in  human  phenomena,  the  fact  remains 
that  these  processes  begin  with  elements  discovered  by 
the  biologist  among  organisms  of  the  lower  levels  in  the 
scale. 


We  come  at  length  to  the  biological  interpretation  of 
human  social  evolution,  in  so  far  as  this  may  be  ex- 
pounded in  a  simple  and  concise  form.  The  compara- 
tive method  must  be  employed  in  order  to  discover  the 
fundamentalattributesofsavage,  barbarous,  and  civilized 
communities  which  seem  to  diiTer  so  considerably  in 
their  complexity  of  social  structure,  and  in  order  also 
to  show  that  such  basic  elements  are  like  those  of  com- 
munities formed  by  lower  animals,  and  are  c(iually  the 
products  of  natural  evolution.  Tliis  whole  subject 
seems  to  be  exceedingly  comi)lex,  because  in  our  daily 
contact  with  others  of  our  kind  and  in  our  occasional 


268  DOCTRINE  OF  EVOLUTION 

views  of  foreign  races  like  our  own,  the  smaller  details 
occupy  our  attention,  diverting  it  from  the  great  basic 
principles  according  to  which  every  society  is  organized 
and  operates.  But  when  once  the  major  elements  have 
been  discovered  in  civilized  and  more  primitive  nations, 
the  secondary  and  less  essential  phenomena  fall  into 
their  proper  relations,  and  a  statement  of  the  whole 
process  of  development  becomes  relatively  simple. 
So  much  space  has  been  devoted  to  lower  types  of 
communal  organisms  in  order  to  learn  what  the  funda- 
mentals are,  and  not  merely  to  provide  analogies  that 
may  be  useful  hereafter.  It  now  remains  to  arrange 
the  evidences  of  social  progress  during  the  history  of 
mankind  itself,  and  to  bring  such  human  facts  into 
relation  with  w^hat  has  been  discovered  in  lower  nature. 
It  is  helpful  to  begin  this  part  of  the  subject  by  asking 
ourselves  what  is  already  part  of  common  knowledge 
about  human  history.  Do  we  know  of  any  civilized 
nation  that  is  absolutely  stable  and  unvarying  in  social 
structure,  or  one  that  has  remained  unchanged  through- 
out historic  time  ?  The  answer  must  be  negative,  for 
in  no  case  does  the  past  disclose  an  example  of  per- 
manence in  social  or  in  any  other  respect ;  monarchies 
and  republics  are  plastic  like  the  human  frame  itself. 
The  American  Commonwealth  is  a  relatively  young 
social  organism,  and  it  is  an  easy  task  to  trace  its  growth 
from  beginnings  in  the  diffuse  and  uncorrelated  colonies 
of  pre-Revolutionary  years.  Those  colonies  that  were 
formed  by  English  settlers  were  transplanted  out- 
growths from  a  civilized  social  parent  which  in  its  turn 
had  clearly  evolved  from  the  state  of  King  John's  time 
and  the  still  cruder  form  it  had  under  King  Alfred. 


SOCIAL  EVOLUTION  AS  A  BIOLOGICAL  PROCESS    200 

Should  we  follow  back  the  recorded  history-  of  any 
people  now  civihzed,  we  would  always  find  evidence  of 
ceaseless  change ;  and  the  writings  of  ancient  historians 
like  Herodotus  and  Caesar  and  Tacitus  give  a  great  deal 
of  information  about  the  barbarous  conditions  from 
which  civilization  evolved. 

But  much  more  is  known  that  materially  amplifies 
the  account  of  human  progress  based  upon  documents 
alone.  The  student  of  existing  human  races  early  learns 
that  social  structure  is  a  very  varied  thing.  The  natives 
of  northern  Africa  now  five  in  a  semi-civilized  state 
which  is  very  hke  that  of  medieval  England.  In 
Siberia  and  the  American  Southwest  are  tribes  that 
correspond  socially  with  the  barbarians  of  Europe  de- 
scribed by  Greek  and  Roman  writers.  The  American 
Indians  discovered  by  the  earliest  colonists,  the  Poly- 
nesians of  a  century  ago,  and  the  Fuegians  of  recent 
decades  provide  counterparts  of  the  ancient  stone- 
wielding  people  who  were  the  savage  ancestors  of  Euro- 
pean barbarians.  Hence  the  comparative  study  and 
classification  of  modern  races  establishes  a  scale  of 
social  grades  which  corresponds  with  the  order  of  their 
historic  succession,  just  as  in  a  larger  way  the  comj^lete 
series  of  comparative  anatomy  from  Arncoba  to  man 
displays  the  order  of  evolution  from  unicellular  be- 
ginnings to  the  present  culminating  types.  Savagery, 
barbarism,  and  civilization  are  the  three  major  terms 
of  this  social  scale,  but  by  no  means  are  they  discon- 
tinuous, for  many  intermediate  forms  of  organization 
occur  which  are  transitional  from  one  major  type  to  a 
higher  one. 

In  human  social  evolution  the  starting  point  is  not  so 


270  DOCTRINE  OF  EVOLUTION 

simple  as  the  solitary  unit  from  which  insect  societies 
evolved,  —  that  is,  an  organism  which  lives  alone  and 
is  associated  with  another  of  its  species  only  at  the  time 
of  mating.  The  lowest  human  beings  now  existing 
have  some  form  of  family  organization,  traceable  to 
the  more  or  less  continuous  unions  formed  among  cer- 
tain of  the  apes  and  even  among  many  lower  animals, 
and  not  a  characteristic  that  belongs  to  mankind  alone. 
The  savage  and  his  mate  constitute  the  social  unit  out 
of  which  all  else  is  built  up ;  the  man  and  the  woman 
must  perform  all  of  the  vital  tasks  demanded  by  nature. 
Fruits  and  vegetables  must  be  secured  from  the  wild 
forest  or  by  cultivation;  the  flesh  of  game  animals 
or  of  a  human  victim  is  no  less  essential  for  food.  The 
savage  is  his  own  weapon  maker  and  warrior ;  he  him- 
self builds  the  rude  shelter  for  his  family  and  fashions 
the  canoe  if  such  is  required.  He  is  also  his  own  judge, 
recognizing  no  control  save  the  dictates  of  his  wishes 
and  needs,  for  he  does  not  consciously  realize  that  he 
must  obey  the  primal  commands  of  nature  to  preserve 
himself  and  his  family  so  that  the  species  shall  persist. 
In  brief,  the  elementary  family  unit  carries  on  all  of 
the  individual  biological  tasks  of  foraging,  fighting, 
home-building,  and  the  like,  and  it  also  discharges  the 
racial  task  of  multiplying,  quite  as  instinctively  as  it 
provides  for  its  own  maintenance. 

By  the  union  of  several  families,  a  primitive  associa- 
tion arises,  like  that  of  the  Veddahs  in  Ceylon.  The 
primal  duties  of  each  family  are  unchanged,  and  their 
biological  activities  are  identical,  as  in  the  protozoon 
colony  of  Vorticella  or  in  a  pack  of  wolves ;  but  certain 
new  relations  are  established.     A  member  of  such  an 


SOCIAL  EVOLUTION  AS  A  BIOLOGICAL  PROCESS    271 

inchoate  tribe  must  not  treat  his  confrt'^ros  as  ho  mip;ht 
a  man  of  another  group;  robbery  and  nnirdcr  within 
the  limits  of  the  small  association  are  detriniontal  to 
communal  interests,  though  they  may  remain  unchecked 
if  the  victims  are  strangers.  Cooperation  for  mutual 
offense  and  defense  makes  the  group  stronger  than  its 
constituent  family  units  taken  singly,  and  every  man 
of  such  a  tribe  gains  something  by  looking  out  for  others 
as  well  as  for  himself.  By  natural  selection  alone  the 
bonds  of  union  would  be  strengthened  in  direct  pro- 
portion to  the  subordination  of  individual  interest 
to  group  welfare,  and  to  the  amount  of  altruistic 
action  that  in  a  true  sense  grows  out  of  purely  selfish 
conduct. 

But  when  such  a  primitive  biological  association  forms 
and  grows,  an  opportunity  arises  for  increasing  the 
effectiveness  of  the  whole  group  by  differentiation. 
Some  of  the  men  are  stronger  in  battle  and  they  soon 
become  the  chief  warriors;  others  prove  to  be  more 
skilful  in  the  hunt  or  in  the  construction  of  canoes  and 
weapons.  Just  as  among  the  insects,  the  hunter  seeks 
food  not  only  for  himself  but  for  the  warriors,  who  in 
their  turn  defend  themselves,  but  do  not  cease  fighting 
when  they  have  disposed  of  their  own  enemies  if  foes 
of  their  comrades  still  survive.  The  barbarous  state  of 
society  thus  arises,  and  the  division  of  labor  brought 
about  during  its  origin  makes  it  possible  and  indeed 
essential  for  many  family  units  to  remain  together  for 
mutual  good.  The  union  is  stable  and  efficient,  how- 
ever, only  if  the  individual  suppresses  his  own  selfish 
inclinations,  suspending  private  quarrels  when  public 
wars  are  toward,  and  acting  at  all  times  in  concert  with 


272  DOCTRINE   OF  EVOLUTION 

his  fellows.  Self-control  increases  necessarily,  and 
lines  of  conduct  deemed  right  by  a  solitary  savage 
unit  come  more  and  more  under  the  sway  of  social 
inhibition,  for  although  the  primitive  savages  must 
inhibit  individualistic  action  to  some  degree,  the  bar- 
barian must  suppress  much  more  of  his  purely  personal 
wishes  for  the  purpose  of  social  solidarity.  Thus  it 
comes  about  that  a  barbarous  community  can  number 
thousands,  while  a  tribe  of  savages  with  a  higher  degree 
of  individualism  and  less  altruism  cannot  cohere  if  it 
comprises  more  than  hundreds  or  scores. 

Civilization  is  a  product  of  evolution  by  precisely  the 
same  natural  mode  of  development,  that  is,  through 
further  subordination  of  individual  to  communal  inter- 
ests and  through  progressive  dividing  up  of  the  tasks 
necessary  for  the  life  of  the  group.  The  final  result 
is  so  obvious  and  familiar  that  we  take  it  for  granted, 
accepting  it  as  self-sufficient  without  realizing  how  it 
has  come  about  and  how  modern  is  the  present  state 
of  affairs.  Let  us  compare  the  life  of  an  Indian  savage 
living  on  Manhattan  Island  four  centuries  ago  with  that 
of  a  New  Yorker  to-day,  as  regards  so  simple  a  matter 
as  the  procuring  of  fish  food.  The  Indian  emerged  from 
his  tepee,  built  by  himself,  and  walking  to  the  shore, 
stepped  into  a  canoe  which  also  he  had  made  with  his 
own  hands.  Paddling  to  the  fishing  ground,  he  pa- 
tiently cast  his  line  until  the  desired  fish  were  caught. 
Does  any  one  of  us  do  all  of  these  things  for  himself? 
We  live  in  houses  constructed  for  us  by  others  who 
devote  their  lives  to  building;  we  are  very  apt  to  go 
about  the  city  in  conveyances  that  demand  special 
and  peculiar  skill  for  their  invention ,  manufacture,  and 


PROPERTY  UBRARY 

Urn  C.  Stale  College 


SOCIAL  EVOLUTION  AS  A  BIOLOGICAL  PROCESS    273 

operation.  Arriving  at  a  market-place,  we  obtain  such 
an  article  of  food  as  a  fish  without  having  to  go  out  upon 
the  water  ourselves,  for  many  other  workers  have  built 
vessels  that  we  do  not  know  how  to  make  and  may  not 
know  how  to  handle,  and  hundreds  of  fishormen  devote 
their  lives  to  their  special  task,  not  for  themselves,  but 
for  us  and  all  others,  such  as  the  builder,  the  subway 
operator,  the  boat  maker,  and  the  manufacturers  who 
supply  their  clothing  and  apparatus. 

What  has  come  about  then  is  a  higlier  degree  of 
specialization  in  the  performance  of  the  fundamental 
biological  tasks,  resulting  in  the  formation  of  coherent 
and  efficient  groups  comprising  millions  as  compared 
wdth  the  thousands  of  barbarism  and  the  hundreds  of 
savagery.  Just  so  the  communities  of  insects  with  the 
greatest  degree  of  altruism  and  division  of  lai^or  far 
exceed  in  numbers  the  small  colonies  of  the  social  wasps 
with  lower  social  differentiation. 

But  the  great  biological  functions  of  an  entire  com- 
plex civihzed  society  remain  the  same  as  those  of  a 
primitive  savage  family  unit,  of  an  insect  community, 
of  Htjdra,  and  of  Amoeba.  Let  any  nation  fail  to  main- 
tain itself  in  material  individual  respects,  it  must  inevi- 
tably die  out ;  in  the  islands  of  the  South  Seas  many  a 
tragic  death-struggle  of  a  people  can  be  witnessed.  If 
in  the  second  place  a  nation  should  concern  itself  too 
greatly  with  the  material  benefits  of  human  life  witliout 
obeying  the  natural  mandate  to  propagate  itself,  iU 
place  in  the  scheme  of  things  becomes  insecure,  as  in 
the  case  of  the  French  Republic.  Natural  social  laws 
that  go  back  to  Ariiocba  must  be  observed,  consciously 
or  unconsciously,  or  else  even  the  civilized  conununiiy 


274 


DOCTRINE  OF  EVOLUTION 


must  fall,  like  scores  and  hundreds  of  others  that  lie 
along  the  road  of  historic  progress  —  a  road  strewn  with 
the  remains  of  the  unfit  thrown  out  by  natural  selection. 


What  now  are  the  lessons  of  social  evolution  and  what 
guidance  does  science  give  for  human  endeavor?  Al- 
though it  may  seem  that  the  biologist  leaves  his  field 
when  he  considers  these  questions,  his  duty  would  be 
unfulfilled  if  he  neglected  an  opportunity  to  give  his 
results  their  highest  utility  through  their  use  for  the 
betterment  of  human  life. 

The  first  lesson  is  that  the  history  of  human  social 
organization  is  far  from  unique,  and  that  it  is  identical 
with  the  process  by  which  insect  communities  and  cell- 
aggregates  have  evolved;  in  a  word,  the  laws  of  bio- 
logical association  are  uniform  throughout  the  entire 
organic  scale.  In  some  respects  evolution  in  mankind 
has  yet  to  equal  the  heights  attained  by  some  insects, 
inasmuch  as  no  human  society  has  accomplished  so  rigid 
a  specialization  of  its  members  that  a  given  individual 
is  foreordained  by  its  inherited  structure  to  be  a  par- 
ticular kind  of  worker  and  nothing  else.  Furthermore, 
evolution  in  human  society  is  still  far  short  of  a  state 
where  some  and  some  only  are  reproductive  members 
of  the  group  while  the  others  are  necessarily  sterile; 
social  insects  with  stable  colonies  are  so  organized  that 
the  queens  and  drones  are  solely  reproductive  while  the 
workers  are  destined  to  care  for  the  material  wants  of 
the  colony.  It  is  true  that  the  birth-rate  is  by  no  means 
the  same  in  all  classes  of  society,  but  the  social  and 
other  adventitious  restrictions  that  bring  this  about  are 


SOCIAL  EVOLUTION  AS  A  BIOLOGICAL  PROCESS   275 

not  on  the  same  plane  with  the  hereditary  determin- 
ing factors  which  operate  among  insects,  'i'horefore 
the  scale  of  human  communities  proves  to  be  only 
a  part  of  the  wider  range  of  organic  associations  in 
general  —  a  part  which  can  be  definitely  placed  in  such 
a  wider  scheme  and  so  become  more  intelligible  in 
itself. 

In  all  departments  of  social  (^volution,  progress  is 
made  by  the  twofold  process  of  combination  and  diiTer- 
entiation.  We  have  dealt  with  detailed  instances,  and 
now  it  is  profitable  to  treat  the  process  in  a  larger  way, 
with  a  view  toward  the  possibilities  of  the  future. 
The  Tliirteen  Colonies,  somewhat  similar  in  their 
earlier  economic  activities,  united  for  nuitual  sui)port 
much  as  wolves  combine  to  form  a  pack.  Later,  as 
circumstances  directed,  they  differentiated  into  farming 
or  manufacturing  or  commercial  organs  of  the  body 
politic,  each  to  some  degree  freeing  itself  of  the  functions 
undertaken  by  others,  and  becoming  thereby  more 
dependent  than  before  upon  those  that  speciahzed  in 
different  ways.  As  in  the  history  of  the  insects  in  a 
growing  wasp  community  and  of  savages  evolving  into 
barbarians,  the  original  condition  of  relative  indepen- 
dence passed  into  a  state  of  interdependence  and  coop- 
eration. In  hke  manner,  if  nature  remains  the  same,  as 
there  is  every  reason  to  believe  it  will,  nations  now  sepa- 
rate will  unite  to  make  more  complex  combinations  that 
will  be  veritable  empires  of  world-wide  scope.  Countries 
on  opposite  sides  of  an  ocean  are  now  more  closely  con- 
nected by  lines  of  communication  and  means  of  travel 
than  were  the  Carolinas  and  New  England  a  century 
ago.     Diplomatic  activities  give  many  signs  of  a  grow- 


276  DOCTRINE  OF  EVOLUTION 

ing  appreciation  of  the  value  of  reciprocal  agreements 
for  mutual  advantage,  and  the  Hague  Conference  is  a 
concrete  manifestation  of  a  continuing  process  of  social 
evolution  that  finds  its  beginnings  and  its  interpretation 
far  below  human  history  in  lower  organic  nature. 

But  perhaps  the  most  important  result  of  this  whole 
discussion  is  the  lesson  of  social  service  that  it  teaches. 
We  are  members  of  a  vast  community  whose  complex 
total  life  seems  far  removed  from  anything  going  on  in 
an  ant-colony,  and  our  daily  tasks  vary  greatly  in 
specific  character  and  degree  when  compared  with  those 
of  lower  communal  organisms.  It  seems  scarcely  cred- 
ible that  any  principles  of  social  relationship,  however 
general,  can  hold  true  for  us  and  for  them.  But  when  the 
rock-bottom  foundations  are  reached,  they  are  simple 
and  instructive  indeed.  Being  here,  we  cannot  escape 
our  personal  obhgations  as  living  things  or  our  equally 
clear  duties  as  members  of  our  community.  These 
facts  being  as  they  are,  what  must  we  do?  Self- 
interest  is  rightly  to  be  served,  otherwise  we  would  be 
incapable  of  discharging  our  secondary  tasks,  namely, 
those  of  service  to  others  in  ways  that  are  determined 
by  hereditary  endowment  and  conditional  circumstances. 
The  difficulty  is  to  find  the  right  compromise  between 
the  two  sets  of  obligations ;  but  the  right  balance  must 
be  found,  or  else  the  health  of  the  community  is  im- 
paired. Should  any  class  demand  more  than  its  just 
dues,  others  must  suffer  through  the  diversion  of  what 
they  require,  and  the  well-being  of  the  selfish  class  is 
jeopardized  to  some  degree,  so  closely  interwoven  are 
the  interests  of  all.  Freedom  of  opportunity  within 
the  limits  of  ability  and  efficiency  is  the  right  of  every 


SOCIAL  EVOLUTION  AS  A  BIOLOGICAL  PROCESS    277 

one,  but  freedom  of  conduct  must  never  result  in  tres- 
pass upon  the  equal  rights  of  others  to  make  the  most 
of  then'  abilities  and  opportunities. 

To  summarize,  then,  social  evolution  is  a  continuous 
process  accomplished  through  differentiation  and  divi- 
sion of  labor  among  the  components  of  biological  asso- 
ciations. Although  the  total  form  remains  the  same 
everywhere,  progress  has  been  made  in  content  through 
the  further  subordination  of  selfish  to  altruistic  conduct ; 
only  by  this  means  does  an  individual  gain  liberty  to 
pursue  the  social  task  for  which  he  is  best  fitted  by 
nature. 


VIII 

EVOLUTION   AND   THE   HIGHER  HUMAN   LIFE 

We  have  now  reached  the  last  division  of  the  large 
subject  that  has  occupied  our  thoughts  for  so  long. 
The  present  title  has  been  chosen  because  the  questions 
now  before  us  relate  to  the  highest  human  ideas  belong- 
ing to  the  departments  of  ethics,  rehgion,  theology, 
science,  and  philosophy.  These  matters  may  seem  at 
first  sight  to  be  far  removed  from  the  territory  of  the  nat- 
urahst  as  such,  and  quite  exempt  from  the  control  of  laws 
which  determine  the  nature  and  history  of  the  human 
individual  in  physical,  mental,  and  social  respects. 
Yet  one  reason  alone  would  impel  us  onward :  we  can- 
not close  the  present  examination  into  the  basic  facts  of 
evolution  and  into  the  scope  of  the  doctrine  without  ask- 
ing to  what  extent  a  belief  in  its  truth  may  affect  our 
earlier  formed  conceptions  of  nature  and  supernature. 
Heretofore  these  possible  effects  upon  what  may  be 
dearly  cherished  intellectual  possessions  have  received 
no  attention,  so  that  we  might  learn  how  evolution 
works  in  the  lower  fields  of  organic  life  in  general  and 
human  life  in  particular  without  being  distm'bed  by 
them.  No  doubt,  however,  the  conviction  has  grown 
with  each  step  in  our  progress  that  the  principles  we 
have  learned  must  cause  us  to  readjust  our  views  of  the 
highest  elements  in  human  thought  to  a  degree  that 
must  be  inversely  proportional  to  our  previous  acquaint- 

278 


EVOLUTION  AND  THE  HIGHER  HUMAN   LIFE     279 

ance  with  the  laws  and  processes  of  nature.  P>ut  tlie 
seeker  after  truth  is  fearless  of  consecjuencos.  He  knows 
that  truth  cannot  contradict  itself;  and  if  those  to 
whom  he  looks  for  authority  give  him  conflict in^  ac- 
counts of  nature's  history,  he  knows  tliat  one  of  these 
must  be  less  surely  grounded  than  the  other.  The 
investigator  soon  learns  to  withhold  final  judgment, 
reahzing  that  the  primary  conditions  for  intellectual 
development  are  the  plasticity  and  openness  of  mind  that 
dogmatism  and  finality  destroy.  He  knows  that  while 
his  researches  may  be,  and  indeed  must  be,  iconochustic, 
they  provide  him  with  better  icons  in  place  of  the  old. 

Let  us  recall  the  steps  in  our  progress  through  one  and 
another  field  of  knowledge,  from  which  representative 
facts  have  been  chosen  for  classification  and  summary. 
We  began  with  the  basic  principles  of  organic  structure 
and  workings,  and  then  we  examined  serially  the  larger 
categories  of  the  evidences  relating  to  evolution  as  a 
fact,  and  to  the  mode  of  its  accomphshment  by  natural 
factors.  Proceeding  to  the  special  case  of  our  own 
species,  we  learned  that  human  beings  are  inevitably  a 
part  of  nature  and  not  outside  it ;  in  structure*,  develoi>- 
ment,  and  palaeontological  history,  mankind  issubject  to 
the  control  of  the  uniform  laws  which  operate  through- 
out the  entire  range  of  living  things.  Finally,  the  men- 
tal characters  and  the  social  relations  of  human  organ- 
isms were  derived  from  beginnings  lower  down  in  the 
scale,  and  were  proved  to  be  no  more  exceptional  than 
the  physical  constitution  of  a  single  human  Ix'ing. 

Are  we  to  forget  all  of  these  things  when  we  try  to  put 
in  order  our  ideas  belonging  to  the  categories  of  higher 
thought?     Can  we  hope  to  fhid  the  truth  if  we  fail  to 


280  DOCTRINE  OF  EVOLUTION 

employ  the  methods  of  scientific  common-sense  which 
only  yield  sure  results?  It  is  no  more  justifiable  to 
discard  our  hard-earned  knowledge  than  it  would  be  for 
an  advocate  to  undertake  the  conduct  of  a  case  in  delib- 
erate disregard  of  what  he  had  learned  of  the  law,  or  for 
a  surgeon  to  leave  his  knowledge  at  the  door  when  he 
entered  the  operating  room.  Too  often  we  are  bidden 
to  view  the  larger  conceptions  of  nature  and  super- 
nature  as  something  outside  the  realm  of  ordered  knowl- 
edge; too  frequently  we  are  given  statements  upon 
authority  that  takes  no  account  of  reason,  and  we  are 
asked  to  accept  these  views  whether  or  not  they  accord 
with  the  demonstrated  facts  of  common-sense.  But 
those  who  have  followed  the  present  description  of  evo- 
lution can  readily  recognize  their  obligation  to  use  for  the 
further  analysis  of  higher  human  life  the  means  which 
have  given  in  that  doctrine  the  most  reasonable  explana- 
tion of  the  natural  phenomena  already  investigated. 

I  need  hardly  say  that  we  now  enter  upon  the  most 
difficult  stage  of  our  progress.  The  regions  we  have 
traversed  were  more  readily  explored  because  they  were 
remote  from  the  matters  now  before  us ;  even  in  the  case 
of  man's  mental  and  social  evolution  it  was  possible  to 
take  a  partially  impersonal  view  of  certain  of  the  essen- 
tial elements  in  human  life,  which  we  cannot  do  now. 
For  ethics  and  religion  and  philosophy  are  groups  of  ideas 
that  are  familiar  to  us  as  the  property  of  mankind  alone. 
Countless  obstacles  are  in  the  way.  Much  mental  inertia 
must  be  overcome,  for  it  is  far  easier  to  accept  the  aver- 
age and  traditional  judgments  of  other  men  —  to  let  well 
enough  alone  —  than  it  is  to  win  our  own  way  to  the 
heights  from  which  we  may  survey  knowledge  more  fully. 


EVOLUTION   AND  THE  IIICilll'.R   HUMAN   LIFE     2S1 

Human  prejudices  confront  us  as  a  veritable  jungle, 
hemming  us  in  and  obstructing  our  vision  on  all  sides; 
and  perhaps  much  underbrush  must  be  cut  away  if  \vc 
are  to  see  widely  and  wisely.  Nevertheless,  to  those 
imbued  with  a  desire  to  learn  truth,  anything  and  every- 
thing gained  must  surely  repay  a  thousand  times  all 
efforts  to  obtain  clearness  of  vision  and  breadth  of  view. 
With  our  perspective  thus  rectified  by  our  backward 
glance,  we  turn  to  the  three  divisions  of  human  thought 
now  to  be  examined.  The  conceptions  of  ethics  come 
first  for  reasons  that  must  be  apparent  from  the  classifi- 
cation of  the  facts  of  social  evolution ;  just  as  mental 
attributes  and  communal  organization  are  inseparai)le, 
so  rules  of  conduct  arise  yari  passu  with  the  origin  of  a 
biological  association.  Religion  and  theology  form  the 
second  division,  which  takes  its  origin  in  part  from 
the  first,  for  these  two  groups  of  ideas  are  largely  con- 
cerned with  the  authority  for  right  conduct  and  with 
human  responsibility  for  taking  tJie  right  attitude  to- 
ward the  entire  visible  and  unseen  universe.  Uinally, 
science  and  philosophy  are  briefly  treated  as  evolved 
products  which  include  within  their  scope  all  that  there 
is  in  human  know^ledge ;  for  this  reason  they  take  the 
highest  place,  instead  of  the  position  below  religion  usu- 
ally assigned  to  them.  At  the  last,  having  reached  our 
final  standing  ground,  we  must  look  back  in  order  that 
we  may  clearly  define  the  lessons  and  ultimate  values 
of  the  whole  doctrine  of  evolution. 


Ethics  is  the  science  of  duty.     It  is  usually  restricted 
to  an  examination  of  purely  human  obligations,  and  to 


282  DOCTRINE  OF  EVOLUTION 

a  search  for  the  reasons  why  men  should  do  certain 
things  and  refrain  from  committing  other  acts.  Like 
psychology  and  sociology,  ethics  began  as  a  strictly 
formal  and  a  priori  system  of  dogmas  which  related  to 
the  life  of  cultured  human  beings  alone.  Again,  like 
the  sciences  specified,  it  gradually  broadened  its  scope 
so  as  to  include  the  conventions  of  races  lower  in  the 
scale  than  the  civilized  peoples  who  only  were  sufficiently 
advanced  intellectually  to  conceive  it.  Thus  the  com- 
parative method  came  to  be  employed,  and  in  direct 
proportion  to  its  use,  more  liberal  views  have  developed 
regarding  the  diverse  methods  of  thought  and  standards 
of  social  life  and  of  conduct  among  differently  condi- 
tioned peoples.  Still  more  important  is  the  demonstra- 
tion that  human  ethics  as  a  whole,  like  human  faculty 
and  civilization,  takes  its  place  at  the  end  of  a  scale 
whose  beginnings  can  be  found  in  lower  organic  nature. 
Those  who  have  followed  the  account  of  social  evo- 
lution given  in  the  preceding  chapter  must  realize  that 
the  basic  general  principles  of  natural  ethics,  as  con- 
trasted with  ^^ formal"  ethics,  have  already  been  dis- 
covered and  formulated.  A  biological  association  of 
whatever  grade  and  degree  of  complexity  is  impossible 
unless  biological  duties  are  discharged.  Human  ethical 
conduct  differs  from  insect  and  protozoon  ethical  con- 
duct only  in  the  element  of  a  participation  in  the  pro- 
cess by  the  explicit  consciousness  of  man  that  he  has 
definite  obligations  to  others;  and  this  distinguishing 
characteristic  is  the  direct  outcome  of  an  evolution 
which  adds  reflection  and  conceptual  thought  to  a  men- 
tal framework  derived  from  prehuman  ancestors.  The 
insect  hurries  about  in  its  daily  life  as  an  animated 


EVOLUTION  AND  THE  HIGHER  HUMAN   LIFE     2^3 

machine,  whose  activities  are  delined  by  heredity ; 
its  special  mode  of  conduct  is  just  what  nature  has  pro- 
duced by  selection  from  among  countless  other  forms 
of  living  which  have  not  had  the  same  degree  of  biologi- 
cal utility.  But  man  alone  recognizes  vaguely  or  clearly 
the  ^Svhy  and  wherefore"  of  his  acts  that  are  far  more 
instinctive  than  he  supposes;  he  only  is  consciously 
aware  of  the  bonds  of  kinship  and  economic  interdepen- 
dence. He  looks  about  for  the  authority  which  imj)()ses 
his  duties  and  fashions  his  bonds,  and  conceives  this 
authority  as  something  superhuman,  until  the  com- 
parative studies  of  evolutionary  phenomena  reveal  the 
true  causes  in  uniform  nature  itself. 

According  to  biological  ethics,  the  fundamental  obH- 
gations  of  all  living  things  are  the  same,  even  though 
the  modes  of  discharging  them  may  be  various.  Every 
individual  must  lead  an  efficient  personal  life  by  i^ro- 
curing  food,  but  animals  differ  very  much  in  their  ali- 
mentary apparatus;  among  other  things  they  must  re- 
spire, but  some  are  so  simply  organized  that  they  do  not 
need  elaborate  organs  like  the  tufted  gills  of  a  crusta- 
cean or  the  lungs  of  higher  vertebrates.  Every  in- 
dividual of  whatever  grade  must  also  provide  in  some 
way  for  the  maintenance  of  the  species,  but  some,  like 
a  conger  eel,  produce  enormous  nunil)ers  of  eggs  whieh 
are  left  uncared  for,  while  others,  like  birds,  bring  forth 
only  a  few  young,  which  receive  constant  attention  and 
protection  until  they  are  able  to  sliift  for  themselves. 
Nature  has  no  place  for  even  a  human  community  un- 
less individual  and  racial  interests  are  conserved,  so 
that  the  greatest  duties  are  defniit(>ly  formulateil  —  all 
else  is  secondary  and  less  essential.     Selfish  action  on 


284 


DOCTRINE   OF  EVOLUTION 


the  part  of  every  unit  is  obligatory,  but  it  must  always 
be  antecedent  to  endeavor  in  the  wider  interests  of  the 
race  if  the  unit  is  a  solitary  individual ;  if  it  is  a  member 
of  an  association  of  any  grade,  then  it  must  serve  its 
fellow^s  in  some  way.  Egoism  and  altruism  are  natural 
essential  guides  to  conduct ;  neither  can  safely  exclude 
the  other,  and  their  antithesis  sets  a  problem  for  every 
organism,  which  is  to  work  out  the  proper  compromise 
that  will  be  most  satisfactory  to  nature.  The  Golden 
Rule  is  taught  by  biology  because  it  is  demonstrated 
empirically,  and  not  because  it  has  any  a  priori  value  as 
an  ideal  ethical  principle. 

But  utilitarian  or  natural  ethics  need  not  stop  with 
the  statement  of  vague  generalities  like  the  foregoing. 
In  human  society,  as  in  the  life  of  low  animals,  the  worth 
and  value  of  any  form  of  conduct  and  of  every  single  act 
can  be  estimated  by  definite  biological  criteria.  The 
institution  of  marriage  and  the  conventions  of  common 
morality  have  their  biological  value  in  their  provision 
for  the  care  of  children ;  the  safeguards  of  property 
rights  enable  the  industrious  —  the  biologically  effi- 
cient —  to  keep  the  fruits  of  their  labors  ;  the  establish- 
ment of  formal  civil  and  criminal  laws  is  biologically 
valuable  in  a  social  way,  in  so  far  as  such  laws  diminish 
the  unsettling  effects  of  personal  animosity  and  the 
desire  to  wreak  personal  vengeance ;  the  establishment 
and  differentiation  of  legislative,  executive,  and  judicial 
organs  of  government  lead  to  greater  social  solidarity 
and  higher  biological  efficiency.  Thus  unchecked  in- 
dividualism is  just  as  wrong  ethically  and  biologically 
among  men  as  it  would  be  in  the  case  of  insect  communi- 
ties, as  pointed  out  in  the  preceding  chapter ;  no  one  has 


EVOLUTION  AND  THE  HIGHER   HUMAN   LIFE     285 

a  right  to  expect  service  or  dcforcnce  to  personal  inter- 
est from  others  if  he  fails  to  work  for  thorn  and  for  the 
good  of  all.  It  is  true  that  the  social  structure  will  stand 
a  great  amount  of  tension,  but  if  this  becomes  too  great, 
either  a  readjustment  is  effected,  as  when  King  John  was 
forced  by  the  barons  to  concede  their  riglits,  or  else  the 
whole  nation  suffers,  owing  to  the  seHi>lin('>s  of  a  few. 
In  the  war  between  Russia  and  Japan,  the  latter  won 
because  the  individual  soldier  merged  his  individuality 
in  the  larger  mechanism  of  the  regiment  and  brigade 
and  army  corps,  gladly  sacrificing  his  life  for  the  nation 
represented  by  the  person  of  its  Emperor.  The  single 
Russian  soldier  may  have  been  far  superior  to  a  Japanese 
in  muscular  strength,  and  perhaps  in  arms  also,  but 
selfishness  and  greed  on  the  part  of  many  who  were  re- 
sponsible for  the  organization  and  e(iuii)ment  of  the 
Russian  armies  rendered  the  whole  fighting  machine 
less  coherent  and  therefore  less  efficient  than  that  of 
the  Japanese. 

In  the  evolution  of  ethics  the  recognition  of  ideals  of 
conduct  has  followed  long  after  the  institution  of  a  par- 
ticular precept  by  nature,  which  is  obeyed  instinctively 
and  mechanically  by  force  of  inheritance.  In  the  case 
of  the  communities  of  insects,  the  results  are  the  same 
as  though  the  individual  animal  fully  recognized  the 
value  of  concerted  endeavor.  So  among  primitive 
savages  of  to-day  there  is  only  a  vague  conception  of 
abstract  duty  as  such,  or  it  may  be  i)ractically  lacking, 
as  in  the  case  of  the  Fucgians.  So  also  a  growing  child 
is  substantially  egoistic,  and  it  must  be  taught  by  prt^ 
cept  and  example  that  the  rights  of  others  can  be  safe- 
guarded only  by  the  altruistic  correction  of  personal 


286        DOCTRINE  OF  EVOLUTION 

action,  long  before  the  child  can  grasp  the  higher  con- 
ceptions of  ethics.  If  a  human  being  never  learns  to  do 
so,  and  becomes  a  criminal  through  force  of  heredity  or 
circumstances,  the  machinery  of  the  law  automatically 
comes  into  operation  to  conserve  the  welfare  of  the  com- 
munity. Such  a  criminal  may  be  unable  to  control  his 
destiny,  and  may  not  be  responsible  for  being  what  he  is, 
but  nevertheless  he  must  pay  the  penalty  for  his  un- 
social heritage  by  suffering  elimination. 

Ethical  systems  are  built  around  man's  vague  recog- 
nition of  certain  natural  obligations,  and  they  have  thus 
become  more  or  less  complex,  and  more  or  less  varied  as 
worked  out  by  different  peoples.  They  must  necessa- 
rily be  much  concerned  with  social  questions,  with 
morals  in  the  usual  sense  and  the  more  rigid  principles 
enacted  into  the  spoken  and  printed  law,  but  they  have 
also  become  closely  connected  with  rehgion  and  theo- 
logical elements.  Especially  is  this  true  in  the  ethics  of 
barbarous  and  savage  peoples,  who  accredit  the  ^'cate- 
gorical imperative"  to  some  supernatural  power,  as  we 
are  to  see  in  a  later  section.  The  one  point  that  comes 
out  clearly  is  that  the  systems  of  conduct  and  duties 
have  evolved  so  as  to  be  very  different  among  various 
races,  and  that  in  the  history  of  any  one  people,  ethics 
has  passed  through  many  varied  conditions.  What 
may  be  deemed  right  at  one  period  becomes  wrong  at 
another  when  conditions  may  be  changed ;  in  medieval 
England  the  penalty  of  death  was  prescribed  for  one  who 
killed  a  king's  deer,  as  well  as  for  a  highway  murderer. 
The  Fijian  of  a  quarter  century  ago  killed  his  parents 
when  they  became  too  old  to  be  effective  members  of 
their  tribe.     And  so  deeply  ingrained  was  this  principle 


EVOLUTION  AND  THE   HIGHER   HUMAN    LIFE    287 

of  duty  that  elderly  people  would  voluntarily  go  to  a 
living  grave  surrounded  by  their  friends  ;  while  in  other 
authentic  eases,  parents  have  first  killed  their  sons  who 
failed  to  obey  the  tribal  law,  and  have  then  committed 
suicide.  We  can  see  how  nature  and  necessity  would 
institute  a  law  requiring  such  conduct  where  a  tribe  must 
carry  on  almost  incessant  warfare  and  where  the  avail- 
able food  supplies  would  be  enough  for  only  the  most 
efficient  individuals.  Infanticide  also  has  been  prac- 
tised for  reasons  of  biological  utility,  as  among  the 
Romans,  who  at  first  maintained  their  racial  vigor  by 
deliberately  ordering  the  death  of  weak  babes.  But  times 
have  changed,  and  ethics  has  become  very  different 
with  passing  decades.  Our  civilization  has  resulted  in 
a  development  of  human  sympathy  as  an  emotional  out- 
growth of  necessary  altruism;  this  motive  directs  us 
through  charitable  institutions  and  hospitals  to  prolong 
countless  lives  which  are  more  or  less  inefficient,  but 
which  do  not  render  the  whole  body  politic  incompe- 
tent in  its  struggle  for  existence. 

Nature  then  has  itself  attended  to  the  development 
and  institution  of  ethics.  As  we  look  back  over  the 
long  series  of  stages  leading  to  our  own  system  of  con- 
duct the  most  striking  feature  of  the  history  is  the  in- 
creasing power  of  self-control  or  inhibition.  As  a  natu- 
ral instinct  this  tends  to  prevent  the  committing  of  acts 
which  for  one  reason  or  another  are  naturally  harmful  to 
society  as  a  whole.  What  we  call  conscience  is  an  in- 
stinct implanted  by  purely  natural  factors,  and  it  un- 
consciously turns  the  course  of  human  action  in  the 
directions  of  selfish  and  altruistic  interests.  Conscience, 
then,  without  ceasing  to  have  validity  and  efficiency,  ap- 


288 


DOCTRINE  OF  EVOLUTION 


pears  on  the  same  plane  with  all  of  the  other  products 
of  evolution  which  owe  their  existence  to  individual  or 
social  utility. 


Theology  and  religion  involve  intimately  related  con- 
ceptions of  the  world,  its  make-up,  and  its  causes. 
Strictly  speaking,  religion  is  a  system  of  piety  and  wor- 
ship, while  theology  deals  more  particularly  with  the 
ultimate  and  supernatural  powers  conceived  in  one 
way  or  another  as  the  God  and  the  gods  who  have  con- 
structed the  universe  and  have  subsequently  ordered 
its  happenings.  A  religion  is  a  group  of  ideas  having  the 
effect  of  motives ;  it  is  dynamic  and  directs  human  con- 
duct. Theology,  on  the  other  hand,  is  more  theoretical 
and  descriptive,  and  its  conceptions,  together  with 
those  of  other  departments  of  human  thought,  give  the 
materials  for  the  formulation  of  the  religious  beliefs 
which  determine  the  attitudes  of  men  toward  all  of  the 
great  universe  in  which  they  play  their  part  and  whose 
mysteries  they  attempt  to  solve. 

Defined  and  distinguished  in  these  ways,  these  two 
departments  of  higher  human  life  present  themselves 
for  comparative  study  and  historic  explanation.  They 
differ  much  among  the  varied  races  of  mankind,  so 
much,  indeed,  that  an  investigator  who  approaches 
their  study  with  a  knowledge  only  of  Christian  religion 
and  theology  finds  it  difficult  at  first  to  recognize  that 
the  same  fundamental  ideas,  although  of  far  cruder 
nature,  enter  into  the  conceptions  of  an  idol- worshiping 
fanatic  living  in  the  heart  of  Africa.  But,  neverthe- 
less, beliefs  that  fall  within  the  scope  of  the  definitions 


EVOLUTION  AND  THE   IIIGIIKIl  IIUM.VN   LIFE    289 

adopted  above  are  to  be  found  amonj^  all  men,  and  they 
must  be  examined  so  that  their  agreements  and  dilTer- 
ences  may  be  demonstrated,  and  their  common  elements 
may  be  explained  as  the  natural  products  of  a  i)roces.s  of 
evolution. 

Such  a  broad  comparative  study,  like  that  of  physical, 
mental,  and  social  phenomena  discussed  heretofore, 
must  be  conducted  objectively ;  that  is,  each  and  every 
particular  belief  of  a  religious  or  theological  nature 
which  can  be  discovered  in  any  race  is  entitled  to  a  i)Iace 
in  the  array  of  materials  which  demand  scientific  treat- 
ment. They  must  be  verified,  classified,  and  summa- 
rized, in  order  that  their  total  meaning  and  value  can 
be  discovered.  It  must  be  strongly  empha^sized  that  for 
such  purposes  the  inherent  validity  and  truth  or  falsity 
of  diverse  religions  are  not  called  into  (juestion  when 
they  are  so  considered  as  objects  of  study;  many  still 
entertain  the  view  that  the  mere  task  of  conducting  an 
analysis  of  a  group  of  religious  beliefs  of  whatever  nature 
must  tend  to  destroy  or  alter  that  system  of  religion  in 
some  way  and  degree.  But  whatever  the  comparative 
student  may  himself  believe,  the  conception  of  Jehovah 
in  the  Hebrew  religion  is  quite  as  legitimate  an  object  of 
study  as  the  Buddhistic  concept  of  Brahma  as  the  Ulti- 
mate Being,  or  the  Polynesian  idea  (^f  Tangaroa  as  the 
god  of  the  waves.  We  would  naturally  be  inclined  to 
exclude  the  last  from  our  own  personal  system  of  piety 
and  worship  as  the  childish  concept  of  an  imaginative, 
adolescent  race;  but  whatever  the  truth  may  be,  the 
fact  of  a  belief  in  Tangaroa  is  as  real  as  tlie  fact  of  Chris- 
tian  belief  in  God.  We  can  no  more  destroy  anyone 
of  these  ideas  by  investigating  its  nature  and  origin  than 


290  DOCTRINE  OF  EVOLUTION 

we  destroy  the  efficacy  of  the  human  arm  when  we  study 
its  muscles  and  bones  and  sinews.  The  former,  like  the 
latter,  take  their  places  among  natural  phenomena  whose 
history  must  be  inquired  into  if  there  are  any  reasons  for 
supposing  that  they  fall  within  the  scope  of  evolution. 
I  would  be  the  last  to  lead  or  to  take  part  in  an  attack 
upon  any  system  of  religion,  but  as  a  student  who  is  in- 
terested in  the  universality  of  organic  evolution,  I  am 
forced  to  scrutinize  each  and  every  authentic  account 
of  a  religion  to  see  if  such  systems  present  objective  evi- 
dence of  the  fact  of  their  evolution  through  the  opera- 
tion of  purely  natural  causes. 

But  before  passing  to  a  detailed  treatment  of  the  anal- 
ysis, synthesis,  and  genesis  of  religious  systems,  let  us  em- 
ploy our  common-sense  for  a  brief  backward  glance  over 
the  known  history  of  familiar  facts.  Every  one  is  aware 
that  the  Christian  religions  of  our  time  and  community 
have  not  existed  forever ;  this,  indeed,  is  indicated  by  the 
way  the  passing  years  are  denominated.  We  call  the 
present  year  1907  Anno  Domini,  and  this  whole  expres- 
sion explicitly  refers  to  the  fact  that  less  than  two  thou- 
sand years  ago  the  Christian  systems  of  piety  and  wor- 
ship collectively  took  their  origin  from  their  Hebrew 
ancestor.  The  same  parent  has  produced  the  relatively 
unchanged  Judaism  of  the  present  day.  Judaism  itself 
evolved  under  the  influence  of  the  Prophets,  of  Moses, 
and  of  Abraham.  Turning  to  Asia,  we  learn  how  Bud- 
dhism evolved  from  Brahmanism.  The  teachings  of 
Mohammed  at  a  later  time  developed  into  the  formu- 
lated precepts  of  the  Koran.  Would  any  one  venture  to 
assert  that  all  or  any  of  these  systems  of  thought  have 
stood  firm  and  immutable  from  the  finite  or  infinite 


EVOLUTION   AND  THE   IIIGIIEIl   HUMAN   LIFE     291 

beginnings  of  time?  Would  any  one  contend  that  the 
creeds  of  Protestantism  have  remained  unchan^^cd  even 
during  the  past  twenty  years  ?  Like  all  d('i)arlrnent,s  of 
human  belief  and  knowledge,  religious  concepts  have 
obviously  altered  in  natural  adjustment  Lu  changing 
times  and  to  advancing  conditions  of  human  intellect; 
and  the  question  turns  to  the  mode  by  which  they  have 
been  modified,  to  see  whether  natural  causes  of  evolu- 
tion have  changed  them,  and  have  originated  their 
earliest  beginnings  at  the  very  outset  of  human  history. 
It  has  been  stated  above  that  every  race  of  mankind, 
however  primitive  or  advanced  it  may  be,  holds  some 
form  of  religious  belief  based  upon  some  concei)tion  of 
the  supernatural  powers  back  of  the  world  ;  and  what 
the  universe  is  conceived  to  be  must  largely  determine 
the  particular  characteristics  of  a  theology,  and  through 
this  the  special  form  of  its  attendant  religion.  We 
have  before  us  a  wide  array  of  types  to  study  and  to 
compare,  w^hich  vary  so  greatly,  partly  for  the  rea^^on 
specified,  that  an  inclusive  definition  of  religion  must  be 
couched  in  very  general  terms.  If  we  define  it  as  the 
attitude  and  reaction  of  a  human  being  conditioned  by 
his  know^ledge  of  the  immediate  materials  and  his  con- 
ception of  the  ultimate  powers  of  the  universe,  its  scope 
is  so  extended  as  to  include  the  ideas  of  the  atheists  and 
agnostics  as  well  as  the  crude  conceptions  of  lower  races 
and  those  systems  of  piety  and  worship  conventionally 
regarded  as  religions  by  civilized  peoj)les.  More  than 
this:  we  cannot  regard  the  total  reaction  of  a  think: 
being  as  essentially  different  in  ultimate  value  from  the 
attitudes  toward  theirworlds  of  animals  lower  than  man. 
The  situation  of  a  well-trained  sheep  dog  is  one  of  pai- 


292  DOCTRINE  OF  EVOLUTION 

tures  and  fences  and  gates,  of  rain  and  sunshine,  of 
sheep,  and  of  a  master  whose  voice  is  to  be  obeyed. 
What  the  dog  may  do  is  partly  determined  by  what  it 
finds  in  its  world  of  animate  and  inanimate  things.  Al- 
though the  animal's  ^^ conception"  of  such  things  must 
be  far  simpler  than  a  human  being's,  nevertheless  its 
life  is  lived  in  reaction  to  all  of  its  surroundings  as  they 
are  presented  to  its  cerebral  apparatus  by  the  proper 
organs.  So  in  the  human  case,  conduct  is  directly  af- 
fected by  the  living  and  lifeless  objects  of  a  total  human 
situation,  the  only  difference  being  that  reflective  con- 
sciousness and  reasoned  interpretation  have  their  share 
in  determining  the  assumed  attitude  in  ways  that  seem 
to  have  no  counterparts  as  such  in  the  mental  lives  of 
lower  animals.  But  whether  or  not  the  similarity  be- 
tween human  religion  and  lower  organic  reaction  be 
admitted,  —  and  the  admission  is  one  that  greatly  facili- 
tates an  understanding  of  evolution  in  this  field,  —  the 
general  resemblance  of  all  religions  in  fundamental 
character  at  least  must  be  accepted. 

Another  general  feature  of  religious  systems  is  their 
complexity.  The  essential  elements  of  all  of  them  are 
few  indeed,  as  we  shall  see  at  a  later  point;  they  are 
beliefs  regarding  ultimate  powers,  human  responsibil- 
ity to  such  powers,  and  future  existence.  These  have 
taken  one  specific  form  or  another  in  various  lines  of 
racial  evolution,  but  aside  from  their  own  changes  they 
have  gathered  about  them  many  other  articles  of  creed 
relating  to  other  departments  of  thought  and  life.  Ethi- 
cal rules  of  conduct  are  so  added,  as  in  the  Hebrew 
religion  where  the  idea  of  Jehovah  involves  God  the 
Ruler  and  Judge  who  imposes  and  administers  the  laws 


EVOLUTION  AND  THE  IIIGIIKR   HUMAN    UVK     293 

of  right  living.  Social  customs  are  almo.Ni  invariably 
intertwined  with  religious  views,  among  savages  a.s  well 
as  among  the  more  advanced  .Mohammedans  whose 
rules  relating  to  family  organization  form  an  integral 
part  of  the  whole  cult.  The  emotional  elements  play  a 
large  part  in  some  cases,  in  the  fanatical  creeds  of  the 
Dervish  and  Mahdist  and  in  the  "revivals"  under  nearer 
observation.  In  Greek  cosmology  and  worshij),  aesthet- 
ics figured  to  a  large  degree.  Temi)eramental  and 
other  psychological  characteristics  have  profound  effects 
upon  rehgions,  which  we  may  illustrate  by  such  extreme 
examples  as  the  austerities  of  New  England  and  Scotch 
Presbyterianism  and  the  contrasted  liberties  of  the 
natural  religions  of  tropical  races.  But  all  of  these  ac- 
cessory elements  belong  to  other  well-delined  de])art- 
ments,  some  of  which  have  already  been  considered, 
and  among  the  materials  of  their  proper  divisions  they 
find  their  interpretation  and  historical  exi)lanati()n  in 
evolution.  It  is  with  the  basic  elements  themselves 
that  we  are  now  concerned. 

Only  within  recent  years  have  systematic  attempts 
been  made  to  classify  religions  on  the  basis  of  impersonal 
objective  study.  Throughout  all  times  men  have  in- 
stinctively set  up  their  own  religion  as  the  only  true  one, 
besides  which  all  others  are  designated  simply  as  false  — 
a  very  natural  distinction,  but  one  which  is  too  naive  for 
science,  as  well  as  one  that  takes  into  account  subjec- 
tive or  personal  values  which  are  not  to  be  considered! 
in  an  objective  comparison  and  analysis.  Tin*  liiigui.**- 
tic  basis  w^as  first  employed  by  Miiller.  with  the  result 
that  religions  were  placed  in  the  category  of  evolution- 
ary accompaniments  of  the  other   mental    posscsisions 


294  DOCTRINE  OF  EVOLUTION 

and  of  the  physical  quahties  of  genetically  connected 
peoples.  Thus  the  nations  of  Europe  that  branched  out 
in  all  directions  from  very  nearly  the  same  sources 
possessed  common  linguistic  characters  and  somewhat 
similar  creeds.  The  Sanskrit-speaking  races  were  the 
original  Brahmins  and  Buddhists.  Ancestor  worship  is 
an  accompaniment  of  the  peculiar  languages  spoken  by 
eastern  Mongolian  peoples.  And  although  the  correla- 
tion specified  is  by  no  means  invariable,  because  a  race 
of  one  stock  can  readily  accept  the  religion  of  a  neighbor 
or  of  a  conqueror,  yet  much  is  gained  through  the  in- 
troduction of  the  idea  of  evolutionary  relationships. 

A  more  logical  classification  frankly  adopts  the  genetic 
method  and  clearly  recognizes  the  direct  effects  of  cultu- 
ral and  intellectual  attainments  upon  the  way  a  reli- 
gious system  becomes  formulated.  In  such  an  arrange- 
ment, similar  to  that  of  Jastrow,  religions  can  be  classed 
as  those  of  savagery,  of  barbarism,  of  advanced  culture, 
and  of  civilization.  Among  the  first  named,  nota- 
bly those  of  Polynesian  and  African  tribes,  beliefs  in 
diversified  ghosts  and  spirits  bulk  largely,  and  every 
moving  thing,  be  it  a  river  or  a  cloud  or  a  tree  or  animal, 
is  held  to  be  animated  by  an  invisible  conscious  genius ; 
the  spirits  reside  in  everything,  as  well  as  in  the  great 
unknown  beyond.  Above  these  in  the  scale  are  the 
religions  of  so-called  primitive  cults,  more  elaborate  and 
formalized  in  the  ancient  beliefs  of  Egypt  and  Assjria, 
but  still  below  those  of  advanced  culture,  which  make  up 
a  third  group.  The  fourth  class  includes  the  religions 
which  tend  to  be  coextensive  with  life,  and  which  enjoin 
the  higher  harmony  of  practical  and  theoretical  con- 
ceptions.    Taking  Christianity  as  an  example,  the  con- 


EVOLUTION   AND   THE  HIGHER   HUM.VN   LIFE   295 

trast  with  the  behefs  of  savagery  brings  out  clearly  the 
nature  of  progressive  development.  Here  religious 
thought  is  no  longer  esoteric,  confined  to  a  chosen  sect 
like  the  Levites  among  the  Hebrews  or  the  shaman  and 
medicine-man  among  the  American  Indians ;  nor  is 
religious  observance  restricted  to  the  innermost  shrine 
of  the  tabernacle  or  sacred  dwelling,  accessible  to  few  or 
only  one.  It  comes  to  be  regarded  as  something  in 
which  each  and  every  individual  can  participate,  and 
a  personal  possession  that  has  a  direct  part  in  determin- 
ing all  forms  of  hiunan  life  and  action.  This  is  another 
way  of  saying  that  the  more  highly  evolved  religions 
owe  their  character  to  the  greatly  varied  and  abundant 
intellectual  elements  which  are  built  into  them.  And 
this  is  why  religion  in  the  highest  form,  more  clearly  than 
in  the  lowest  forms,  is  to  be  spoken  of  as  an  outlook  upon 
the  world  which  is  determined  by  the  total  intellectual 
equipment  of  the  individual  man  who  thinks  about  the 
universe  and  directs  his  course  of  action  by  what  he  finds. 


We  come  now  to  a  closer  concrete  study  of  the  basic 
elements  of  religion ;  that  is,  of  those  beliefs  that  are  in- 
variably present,  in  one  form  or  another,  in  every  system 
of  piety  and  worship,  and  that  constitute  the  innermost 
framework  beneath  the  secondary  creeds  added  to 
them.  Following  Mallock  and  others,  we  may  dis- 
tinguish three  such  elemental  conceptions.  These  are, 
first,  the  belief  in  the  existence  of  a  supernatural  being 
or  beings,  endowed  with  intelligence  like.  l)Ut  superior  to, 
our  own;  second,  the  idea  of  human  responsibility  to 
this  or  these  powers  ;  and,  third,  the  belief  in  immortahty 


296 


DOCTRINE  OF  EVOLUTION 


as  an  attribute  of  the  supreme  powers  and  of  human  in- 
dividuals also.  Let  us  see  how  these  beliefs  appear  in 
characteristic  systems  of  religion. 

In  all  forms  of  Christianity  the  central  idea  is  the  con- 
ception of  a  triple  unity  personified  as  God.  He  is  re- 
garded as  the  Creator  who  has  made  all  things  and  who 
demands  reverence  from  his  subjects.  He  is  the  Author 
and  Finisher  of  the  faith  as  well  as  the  sole  Cause  of  the 
universe  itself.  Much  of  this  element  is  directly  derived 
from  Judaism,  the  progenitor  of  Christianity ;  but  a  dif- 
ference consists  in  the  triple  nature  of  the  supreme  being 
according  to  the  newer  creed.  As  the  original  and  su- 
preme being,  God  is  not  only  the  Creator,  but  the  watch- 
ful Judge  as  well,  demanding  reverent  obedience  to  the 
laws  of  the  world  in  which  he  has  placed  man,  and  im- 
posing sacrifices  and  penitential  observances  when  his 
mandates  have  been  disobeyed.  As  the  God  of  Mercy 
he  is  incarnated  in  the  person  of  Jesus  of  Nazareth,  and 
offered  as  a  vicarious  sacrifice  for  sinners  who  are  thus 
enabled  to  escape  the  penalties  they  would  otherwise 
have  suffered.  As  the  Holy  Ghost,  God  is  the  vaguely 
personified  ultimate  source  of  the  higher  and  nobler 
elements  of  human  thought,  aspiration,  and  life  in  gen- 
eral. The  second  basic  tenet  of  Christianity  is  that  of 
human  responsibility  to  God,  to  whom  man  is  related 
as  the  created  to  a  creator,  as  a  subject  to  a  ruler,  and  as 
one  saved  to  his  redeemer.  The  institutions  of  sacrifice 
and  ritual  are  outward  signs  of  human  subjection  to  God 
himself  and  to  his  laws,  according  to  which  the  universe 
is  conceived  to  operate.  Finally,  Christianity  teaches 
that  just  as  God  in  his  single  and  triune  form  is  eternal, 
so  the  soul  of  man  is  immortal,  with  or  without  its 


EVOLUTION  AND  THE  iii(;iii:r  human  ui\.    . .; 

earthly  temple  of  flesh  and  blood.  Tlie  essential  think- 
ing individual  is  believed  Lu  pass  to  heaven,  where 
rewards  for  right  living  are  bestowed,  or  to  hell,  in  order 
to  suffer  punishment  for  sin  during  all  eternity,  or  some 
part  of  it,  according  to  dilTerent  views  reganling  the  elii- 
cacy  of  Christ's  vicarious  atonement. 

It  is  true  that  the  manifold  sects  of  Christianity  difTer 
somewhat  in  the  detailed  forms  of  these  three  essential 
beliefs,  but  not  to  the  same  degree  as  in  the  case  of  the 
secondary  additions.  God's  laws,  Christ's  teachings, 
and  the  inspiration  of  the  Holy  ( Ihost  are  the  recognizeil 
guides  to  conduct ;  but  human  frailty  has  been  such  that 
the  history  of  Europe  presents  a  panorama  of  warring 
sects  in  almost  unceasing  strife  about  details  of  ritual  and 
interpretation,  while  the  great  fundamental  truths  have 
been  too  frequently  ignored.  The  conflicts  of  Catholics 
and  Protestants,  Puritan  and  Cavalier,  and  Northern 
and  Southern  Presbyterianism,  have  not  been  waged  on 
account  of  basic  beliefs  like  the  three  outlined  above,  or 
about  the  Golden  Rule,  but  on  account  of  comj)aratively 
trivial  details  which  to  the  impersonal  stuilent  have 
scarcely  more  than  the  value  of  individual  preference. 

Judaism,  the  next  great  religion,  has  already  been 
mentioned  as  the  parent  of  Christianity,  to  which  it  gave 
the  concept  of  a  Supreme  Being,  as  well  as  that  of  a  Mes- 
siah. It  is  a  purer  monotheism  than  its  outgrowth, 
whose  trinity  is  more  hke  certain  elements  of  Greek 
theology.  Jehovah  is  the  one  supernatural  power,  the 
creator  and  lawgiver  and  immediate  cause  of  all  the 
workings  of  nature.  It  is  he  who  shai)es  the  world  out 
of  nothingness  and  who  separates  the  waters  from  the 
dry  land;   he  parts  the  waters  of  the  Red  Sea  to  save 


298  DOCTRINE  OF  EVOLUTION 

the  Israelites,  and  brings  them  together  again  to  over- 
whelm the  pursuing  hosts  of  Pharaoh.  It  is  his  voice 
that  thunders  from  Mt.  Sinai,  and  his  finger  that  traces 
the  commandments  to  rule  the  lives  of  his  chosen  people 
upon  the  tablets  of  stone  intrusted  to  Moses  the  Seer. 
At  the  behest  of  Joshua  he  holds  the  sun  and  the  moon  in 
their  courses  above  the  vale  of  Ajalon  so  that  there  will 
be  more  time  for  the  destruction  of  the  Philistines.  In 
brief,  Jehovah  is  the  eternal  god  of  law  and  power,  de- 
manding sacrifice  and  priestly  atonement,  and  promis- 
ing happiness  eternal  upon  the  bosom  of  Abraham  to 
those  who  recognize  their  responsibility  to  him  and 
obey  his  precepts.  Again,  there  are  three  fundamental 
beliefs,  that  differ  from  those  of  Christianity  as  the 
Talmud  diverges  from  the  New  Testament  scriptures. 

Mohammedanism  is  another  outgrowth  from  this 
group  of  religions.  The  teachings  of  the  Koran  give  the 
institutional  and  ritual  forms  to  the  same  three  elements 
distinguished  above.  God  is  the  identical  single  God; 
and  Mohammed  is  His  Prophet,  as  Jesus  is  the  New 
Prophet  of  Christendom.  The  true  believer's  responsi- 
bility entails  active  warfare  upon  the  heretics,  that  is, 
those  who  do  not  accept  the  Koran.  The  immortal 
state  of  Mohammedanism  is  a  very  different  thing  from 
the  heavenly  bliss  of  Christianity,  for  the  promised 
rewards  are  such  as  would  appeal  to  the  warm-blooded 
Southern  temperament. 

Turning  now  to  Asia,  we  find  in  Brahmanism  and  Bud- 
dhism two  systems  of  religion  that  are  related  to  one 
another  exactly  as  are  Judaism  and  Christianity.  The 
analogue  of  the  Old  Testament  is  a  group  of  priestly 
hymnal  writings  known  as  the  Vedas,  which  date  back 


EVOLUTION   AND  THE   IIIGIII:R   lU'MAN   LUK     299 

to  about  the  fourteenth  century  before  Clirist  lived. 
Their  objects  of  worship  at  first  arc  numerous  invisible 
beings  that  actuate  the  tilings  of  the  world,  a.s  in  (lre<'k 
theology,  but  later  one  of  I  hem  assumes  [)rei'minence  a.s  the 
all-pervading  essence  of  things,  —  Brahma.  The  precepts 
of  Brahmanism  enjoined  adoration  of  the  unseen  powers 
and  of  their  works,  as  well  as  practical  rules  of  human 
conduct,  such  as  those  which  divided  a  man's  life  into 
the  four  periods  when  he  should  besuccessively  a  student, 
the  head  of  a  family,  a  counselor,  and  a  religious  men- 
dicant who  should  renounce  the  world  of  social  activities 
and  human  desires.  In  earlier  writings,  the  inunortal 
state  is  a  kind  of  heaven,  but  later  it  meant  simi)ly  an 
absorption  into  Brahma,  the  eternal  im])ersonal  being. 
Buddha  was  an  orthodox  Brahman  reformer  of  the 
sixth  century  before  our  present  era,  just  as  Jesus  was  an 
orthodox  Hebrew  reformer.  The  essential  creed  of 
Buddha  made  his  religion  far  more  ethical  than  earlier 
forms,  and  placed  it  on  a  plane  even  above  Christianity 
of  later  centuries.  This  creed  relates  to  the  element  of 
human  responsibility  particularly,  the  other  two  remain- 
ing much  as  they  were  found  by  Buddha.  According 
to  his  teachings,  a  man  rested  under  an  obligation  to  live 
nobly  in  the  truest  sense,  and  he  accjuired  merit  — 
karma  —  or  lost  it,  in  proportion  to  his  deserts.  .\t 
death  a  human  soul  is  reincarnated,  in  a  lower  form  of 
animal  or  even  in  a  being  residing  in  one  of  a  series  of  un- 
seen hells,  if  punishment  is  due  ;  if  a  higher  state  is  mer- 
ited, progress  is  made  through  thousands  of  existences 
until  perfection  is  rewarded  by  an  eternal  fusion  with 
the  essence  of  Brahma.  It  is  because^  there  is  no  escafK? 
from  just  punishment  that  Buddhism  in  its  original  form 


300  DOCTRINE  OF  EVOLUTION 

is  properly  denoted  more  ethical  than  a  religion  which 
teaches  that  sacrifice  of  any  kind  will  exempt  the  sinner 
from  deserved  penalties  and  bring  about  the  bestowal  of 
unearned  rewards. 

Polytheism  is  the  name  given  to  a  religion  such  as  that 
of  the  Greeks  or  Romans,  who  believed  in  many  gods 
and  spirits  of  greater  and  lesser  power.  These  super- 
natural beings,  each  in  its  own  sphere,  immediately 
directed  the  processes  of  nature  and  controlled  the  lives 
of  men.  One  of  them,  Zeus,  was  regarded  as  the  su- 
preme ^^ father  of  gods  and  men,"  who  delegated  specific 
duties  to  others ;  Ares  was  the  god  of  battles,  Hermes 
was  the  messenger,  Athena  implanted  wisdom  in  the 
minds  of  men,  and  Poseidon  ruled  the  sea.  The  gods 
were  very  human  to  the  Greek  mind,  living  in  Olympus  as 
men  do  upon  earth,  and  even  visiting  the  mortals.  Their 
worship  involved  propitiatory  sacrifices  and  rites  as  well  as 
thanksgiving  offerings  when  favors  were  bestowed.  But 
although  they  were  immortal,  they  did  not  allow  the  im- 
mortal souls  of  human  beings  to  join  them  in  their  elysium, 
but  compelled  the  disembodied  shades  to  wander  un- 
happily among  the  tombs  and  about  their  earthly  abodes. 

Roman  theology  and  religion  comprise  almost  identi- 
cal forms  of  the  three  fundamental  elements.  The  names 
are  changed,  and  Zeus  becomes  Jove,  his  wife  Hera 
is  Juno,  Ares  is  Mars,  and  Hermes  is  called  Mercury. 
In  all  other  respects,  however,  the  two  systems  are  as 
much  alike  as  the  Greek  and  Roman  languages  and 
Greek  and  Roman  physique. 

The  religions  of  savagery  are  far  less  analytical,  and 
much  more  naive  in  their  reference  of  natural  happen- 
ings to  the  direct  interposition  of  malevolent  and  be- 


EVOLUTION  AND  THE  IIIGIIKIl   IIUM.VN   LII  K     301 

nevolent  spirits.  Their  gods  are  numerous  as  in  Greek 
religion,  and  likewise  one  of  them  is  usually  set  up  as  the 
superior  deity,  to  be  the  Tirawa  of  the  Indian,  the 
greater  Atua  of  Polynesia,  and  the  Muniho  Jumbo  of  a 
West  African  negro.  There  is  no  centralization  of  the 
supernatural  powers,  as  in  the  Jehovah  of  Judaism  and 
the  still  subtler  Brahma  of  the  Asian.  Then,  too,  the 
gods  must  be  concretely  materialized  for  purposes  of 
worship  and  sacrifice;  consequently  idols  are  made,  to 
be  regarded  as  the  actual  spirits  themselves  permanently 
or  for  the  time  being,  and  not  viewed  as  representations 
of  an  ideal,  like  the  statues  of  more  advanced  peoples. 
The  immortal  state  is  d^cribed  in  low  religions  in 
various  w^ays  that  seem  to  be  determined  by  wliat  the 
believer  himself  most  desires.  The  spirit  of  an  Ameri- 
can Indian  goes  to  the  hapi)y  hunting-grounds,  where  it 
mounts  a  spirit  pony  and  forever  jjursues  the  ghosts 
of  bison  which  it  kills  with  spirit  bow  and  arrows;  to 
provide  these  necessaries  his  earthly  possessions  are  laid 
beside  his  dead  body.  The  Norseman  was  conducted 
to  Valhalla  and,  attended  by  the  Valkyrie  as  hand- 
maidens, he  eternally  drank  mead  from  the  skull  of  an 
enemy  and  gloried  over  his  nmndane  ])rowess  in  battle. 
It  is  unnecessary  to  expand  the  foregoing  list,  because 
the  examples  sufficiently  represent  the  various  grades 
of  human  religions.  Regarding  them  as  typical,  we  ran 
see  how  universal  are  the  three  fundamental  ideas  with 
which  we  are  concerned.  I^xcry  race  has  its  own  con- 
ception of  future  bliss,  as  well  as  its  conception  of  respon- 
sibility to  the  immortal  and  supernatural  powers  of  the 
universe.  Whatever  may  be  the  actual  reality,  and 
however  closely  the  conceptions  of  one  or  another  re- 


302  DOCTRINE  OF  EVOLUTION 

ligion  may  approximate  to  the  truth,  such  reahty  and 
approximation  are  not  the  subjects  of  the  present  discus- 
sion. Nor  is  it  our  purpose  to  bring  out  more  expUcitly 
the  genetic  relationship  of  one  reHgion  to  another ;  the 
evolution  of  Buddhism  from  Brahmanism,  the  origin 
of  Christianity  from  Judaism,  and  the  divergent  de- 
velopment of  the  several  creeds  of  Christendom  amply 
illustrate  the  nature  of  religious  history.  It  is  evolu- 
tion here  as  elsewhere  and  everywhere. 


Having  distinguished  the  three  general  elements  of  all 
religions,  beyond  which  everything  else  is  of  minor  impor- 
tance, we  now  turn  to  the  question  as  to  the  natural  origin 
of  these  elements.  Clearly  they  cannot  arise  independ- 
ently, for  the  behef  in  supernatural  and  eternal  spirits  is 
closely  connected  with  the  conception  of  an  immortal  soul. 

The  first  is  the  conception  of  infinite  personalities  that 
later  become  more  or  less  merged  into  one  supreme  being. 
This  begins  with  the  idea  of  the  soul  as  the  human  ego, 
conventionally  regarded  as  something  independent  of 
the  material  body  during  life  and  immortal  after  death. 
The  savage  goes  to  sleep,  and  in  his  dreams  he  goes 
upon  journeys  and  battles  strenuously  with  other  men 
and  with  beasts,  only  to  find  when  he  awakes  that  his 
body  is  not  fatigued,  and  that  it  has  not  really  taken 
part  in  the  activities  of  his  dream  life.  His  companions 
about  the  fire  also  tell  him  that  this  is  so,  while  he  is 
equally  sure  that  his  essential  self  has  been  doing  many 
things  during  the  interval  of  sleep.  In  his  dream  life  he 
finds  himself  joined  by  others  whom  he  knows  are  dead. 
He  sees  again  even  those  whose  bodies  he  may  have  as- 


EVOLUTION  AND   THE   HKIIIKR  HUM.\N    LL  ,      303 

sisted  in  eating.  Ilis  total  world  very  soon  comee  to 
have  an  unseen  region  which  is  the  abode  of  ordinarily 
invisible  beings  having  the  forms  of  men,  with  whom  his 
own  dream  person  can  associate;  this  unn-m  ^jihere  i« 
furnished  also  with  ghostly  counterparts  of  the  tret-s  and 
rocks  and  waters  with  wliidi  he  is  familiar  when  he  ia 
awake.  Before  long  his  soul  or  ghost  or  spirit  is  con- 
ceived as  something  which  possesses  two  cpialitics:  it 
can  be  disassociated  from  his  body  and  enter  the  spirit- 
world  where  it  seems  to  defy  all  the  laws  of  waking  ! 
for  with  the  cjuickness  of  thought  it  visits  n('ighl>oring 
islands  as  readily  as  it  passes  to  the  next  hut ;  and  it 
possesses  immortality,  for  it  is  exactly  like  the  persistent 
spirit-individualities  of  those  who  have  died  lx»fore  him. 
The  other  cause  for  the  development  of  the  cone  ii 
of  gods  and  God  in  the  mind  of  the  savage  is  the  fact 
that  things  have  been  made  which  neither  he  nor  any 
other  man  can  make.  He  can  dig  a  ditch,  and  make  a 
house,  and  fashion  a  canoe,  and  build  ramparts  of  earth  ; 
but  human  power  has  obviously  been  insuflicient  to  con- 
struct rivers  and  mountains  and  forests  and  their  deni- 
zens. Mankind  itself  has  certainly  been  made  in  some 
way,  for  it  exists.  Because  the  savage  cannot  conceive 
of  things  being  made  excepting  as  they  are  made  l)y  the 
human  hand,  and  because  so  much  confronts  him  that  is 
beyond  the  power  of  human  construction,  he  comes  to 
postulate  the  existence  of  man-like,  but  greater  than 
human,  personalities,  and  a.s  he  cannot  see  them  in  the 
Ught  of  day,  they  belong  to  the  spirit-worid  to  which 
souls  go.  Imagination  sometimes  gives  human  outlines 
to  shadows  among  the  moon-lit  trees,  so  that  elves  and 
pixies,  nymphs  and  fairies,  become  estal  \  in  the 


304  DOCTRINE   OF  EVOLUTION 

world  as  the  primitive  man  conceives  it.  Larger  tasks 
are  discharged  by  more  important  spirits,  and  every- 
thing natural  thus  becomes  animated  by  supernatural 
beings.  Thor  was  the  god  of  thunder ;  Freia  the  god- 
dess of  spring  and  vernal  awakening ;  Athena  inspired 
the  minds  of  men.  Venus  and  Aphrodite  played  their 
special  parts,  also,  ^ut  such  powers  as  these,  estab- 
lished by  the  untutored  mind,  needed  to  be  accounted 
for,  and  so  in  the  more  advanced  religions  Jove  and 
Jupiter  were  created  as  the  more  ultimate  causes,  in 
response  to  intellectual  demands.  By  combining  all 
powers  into  one,  God  and  Brahma  are  the  results. 

Thus  in  merest  outline  the  conception  of  the  infinite 
personality  works  out  its  evolution.  At  all  times, 
among  primitive  and  higher  religions,  the  powers  are 
clothed  with  human  forms,  and  gods  are  pictured  as 
men  endowed  with  intellects  and  passions,  and  motives  of 
vengeance  and  betiignity.  Man  cannot  shape  his  postu- 
lated deities  save  in  such  forms,  with  the  possible  excep- 
tion of  the  most  philosophical  concept  of  all,  Brahma. 

The  second  fundamental  belief,  namely,  in  immortality, 
owes  its  origin  in  greatest  measure  to  the  psychological 
processes  described  above.  Another  potent  factor,  how- 
ever, has  been  the  natural  desire  to  continue  existence 
hereafter,  usually  in  order  to  reap  rewards  not  bestowed 
here.  This  desire  is  implanted  by  nature  through  the 
operation  of  purely  biological  factors,  and  it  has  the 
value  of  an  organic  instinct.  To  specify  more  particu- 
larly, nature  has  placed  every  organic  individual  under 
the  necessity  of  doing  its  utmost  to  prolong  its  own  Hfe 
in  the  interests  of  itself,  of  others  of  its  tribe,  and  of  its 
species.     Extinction  is  not  faced  willingly  by  a  human 


EVOLUTION  AND  THE   HIGHER   HUMAN   LIFE     305 

being  endowed  with  full  consciousness  any  more  than  it 
is  passively  tolerated  by  a  lower  animal  which  instinc- 
tively struggles  with  its  foes  until  death.  So  the  desire 
to  continue  alive  —  the  ''will  to  hve"  —  is  a  natura^in- 
stinct,  which  combines  with  the  belief  in  jiersistent  dis- 
embodied spirits  and,  no  doubt,  with  many  other  ele- 
ments, to  develop  the  basic  conception  of  some  kind  of 
an  immortal  existence. 

The  third  element,  human  responsibility  to  the  infinite 
personality,  is  variously  recorded  in  lower  and  liigher 
religions.  Its  conception  grows  partly  out  of  the  feel- 
ings of  awe  and  terror  inspired  by  great  works  of  nature 
such  as  the  thunder-storm,  the  cyclone,  and  the  volcano, 
while  the  orderly  and  regular  workings  of  even  everyday 
nature  seem  to  demonstrate  the  direct  control  of  the 
powers  who  rule  man  as  well.  The  savage  sees  his  crops 
destroyed  by  a  tempest  or  drought ;  he  attributes  the 
disaster  to  the  particular  powers  concerned  with  such 
things  whom  he  must  have  angered  unwittingly,  and 
whom  he  must  propitiate  by  sacrifice  or  penitence. 
His  individual  and  tribal  acts  do  not  always  accomplish 
the  desired  ends,  and  again  the  laws  of  infinite  and  ulti- 
mate powers  must  have  been  contravenetl,  as  he  inter- 
prets the  situation.  Therefore  his  whole  religious  con- 
sciousness was  exerted  in  the  direction  of  finding  out 
what  was  the  ultimate  constitution  of  nature,  with 
which  human  activities  must  harmonize  if  they  are  to  be 
successful.  Bound  by  custom  and  convention  and  bio- 
logical law,  he  looks  about  wondc^ringly  to  find  the  exter- 
nal authority  for  his  bonds.  To  liis  mind  this  authority 
must  be  the  host  of  spirits  and  gods  who  had  made  him 
and  the  things  of  his  world.     It  is  in  this  way  that  so  many 


306  DOCTRINE  OF  EVOLUTION. 

ethical  elements  have  found  places  in  religious  doctrines, 
to  be  viewed  as  absolute  rules  of  conduct  coming  from 
outside  of  nature,  and  not  from  nature  itself,  in  the  way 
the  earlier  sections  of  this  chapter  have  shown. 

Let  us  now  summarize  the  results  of  the  foregoing 
brief  survey,  conducted  by  the  identical  methods  em- 
ployed for  the  analysis  of  other  bodies  of  fact.  We 
have  sought  for  those  characteristics  which  are  common 
to  all  rehgions  of  whatever  time  and  place  and  race. 
Combined  with  many  secondary  and  adventitious  ele- 
ments of  other  fields  of  thought  and  action,  such  as  social, 
political,  ethical,  and  psychological  factors,  they  have 
proved  to  be  the  three  essential  beliefs  in  God  or  gods, 
human  responsibility,  and  immortality.  As  a  veritable 
backbone,  they  underlie  and  support  the  whole  body 
of  religious  doctrine  and  organs  of  thought  formed  about 
them.  We  have  seen,  furthermore,  that  a  natural  ex- 
planation of  the  way  these  elements  have  originated  can 
be  discovered  by  the  comparative  student  of  religion, 
who  describes  also  how  they  have  variously  evolved 
among  different  peoples.  In  all  of  this  we  have  not 
questioned  at  any  time  the  validity  or  reality  of  any  one 
of  these  concepts ;  to  ask  whether  or  not  they  corre- 
spond actually  to  the  truth  is  beyond  our  purpose,  which 
is  simply  and  solely  to  inquire  whether  even  these  mental 
conceptions  furnish  evidence  of  their  evolution  in  the 
course  of  time.  I  believe  that  such  evidence  is  found, 
and  I  believe  also  that  this  discovery  must  be  of  the 
greatest  importance  to  everyone  in  formulating  a  system 
of  religious  belief,  but  the  construction  of  this  is  not  the 
task  of  science  as  such.  Every  individual  must  work 
out  his  own  relation  to  the  world  on  the  basis  of  knowl- 


EVOLUTION  AND  TIIK   HIGHER  HUMAN   LIFE     307 

edge  as  complete  as  he  can  make  it,  but  every  individual 
must  accomplish  this  end  for  himself.  Jiecause  no  two 
men  can  be  exactly  alike  m  temperament,  intellect,  and 
social  situation,  it  is  impossible  for  entire  agreement  in 
religious  faith  to  exist.  One's  outlook  upon  th<'  whole 
universe  is  and  must  be  an  individual  matter;  science 
and  evolution  are  of  overwhelming  value,  not  by  direct- 
ing the  mind  to  adopt  this  or  that  attitude  toward  the 
unseen,  but  by  providing  the  seeker  after  the  truth  with 
definite  knowledge  about  the  things  of  the  world,  so  that 
his  position  may  be  taken  on  the  sound  ba^is  of  rea.son- 
able  and  common-sensible  principles. 


When  we  take  up  science  and  philosophy,  or  knowl- 
edge as  a  whole,  after  religion,  it  may  seem  that  we  have 
reversed  the  proper  sequence.  There  are  many  reasons 
for  following  this  course,  inasmuch  as  "knowledge"  is 
the  all-inclusive  category  of  thought ;  our  world  is  after 
all  a  world  of  individual  consciousness  and  ideas.  In 
dealing  with  religion,  ethics,  social  organization,  and  hu- 
man culture,  we  have  been  concerned  with  the  evolu- 
tion of  so  many  departments  of  thought  and  action; 
and  now  we  are  to  develop  a  final  conception  of  evolution 
as  a  universal  process  in  the  progress  of  all  knowledge. 

Let  us  look  back  over  the  history  of  mathematics. 
The  primitive  human  individual  did  not  need  to  count. 
He  dealt  with  things  as  he  met  them,  and  lie  disposed 
of  them  singly  and  individually.  A  squirrel  does  not 
count  the  nuts  it  gathers ;  it  simply  accumulates  a  store, 
and  it  perishes  or  survives  according  to  its  instinctive 
ability  to  do  this.     Just  so  was  primitive  man.     The 


308  DOCTRINE  OF  EVOLUTION 

savage,  when  he  organized  the  first  formed  tribes,  learned 
to  count  the  days  of  a  journey  and  the  numbers  engaged 
on  opposite  sides  in  battle.  He  employed  the  ^' score" 
of  his  fingers  and  toes,  and  our  use  of  this  very  word  is  a 
survival  of  such  a  primitive  method  of  counting.  The 
abacus  of  the  Roman  and  Chinese  extended  the  scope 
of  simple  mathematical  operations  as  it  employed  more 
symbolic  elements.  With  the  development  of  Arabic 
notation  capable  of  indefinite  expansion,  the  science 
progressed  rapidly,  and  in  the  course  of  long  time  it  has 
become  the  higher  calculus  of  to-day.  The  conceptions 
of  geometry  have  likewise  evolved  until  to-day  mathe- 
maticians speak  of  configurated  bodies  in  fourth  and 
higher  dimensions  of  space,  which  are  beyond  the  powers 
of  perception,  even  though  in  a  sense  they  exist  concep- 
tually. The  behavior  of  geometrical  examples  in  one 
dimension  leads  to  the  characteristics  of  bodies  in  two 
dimensions.  Upon  these  facts  are  constructed  the  laws 
of  three-dimensional  space  which  serve  to  carry  mathe- 
matical thought  to  the  remoter  conceptual  spaces  of 
which  we  have  spoken.  It  may  seem  that  we  are  record- 
ing only  one  phase  of  mental  evolution,  but  in  fact  we  are 
dealing  with  a  larger  matter,  namely,  with  the  progres- 
sive evolution  of  knowledge  in  the  Kantian  category  of 
number. 

Natural  science  began  with  the  savage's  rough  classi- 
fication of  the  things  with  which  he  dealt  in  everyday 
life.  As  facts  accumulated,  lifeless  objects  were  grouped 
apart  from  living  organisms,  and  in  time  two  great  divi- 
sions of  natural  science  took  form.  Physics,  chemistry, 
astronomy,  geology,  and  the  like  describe  the  concrete 
world  of  matter  and  energy,  while  the  biological  sciences 


EVOLUTION  AND  THE   HIGHER   HUMAN   UFE     309 

deal  with  the  structure,  devclopinont,  intcrrehition- 
ships,  and  vital  activities  of  animals  and  jjlants.  Surely 
knowledge  has  evolved  with  the  advance  in  all  of  tliese 
subjects  from  decade  to  decade  and  from  year  to  year. 
And  just  as  surely  must  evolution  continue,  for  the  world 
has  not  stopped  developing,  and  therefore  the  ^reat 
principles  of  science  must  undergo  further  changes, 
even  though  they  are  the  best  summaries  that  can  be 
formulated  at  the  present  time. 

Philosophy  deals  with  general  conceptions  of  the  uni- 
verse. When  we  look  back  through  the  ages  we  find 
men  picturing  the  world  as  an  aggregate  of  diverse  and 
uncorrected  elements  —  earth,  air,  fire,  and  water.  The 
synthesis  of  facts  and  the  construction  of  general  prin- 
ciples dowi;i  through  Bacon,  Newton,  and  Schopenhauer 
to  modern  world  conceptions  results  in  the  unification  of 
all — ''the  choir  of  heaven  and  furniture  of  earth." 
The  lineal  descendant  of  the  long  fine  of  ancestral  phi- 
losophies is  the  monism  which  sees  no  difference  between 
the  living  and  lifeless  worlds  save  that  of  varying  com- 
binations of  ultimate  elements  which  are  conceived  as 
uniform  ''mind-stuff"  everywhere.  Whether  or  not 
this  universal  conception  of  totality  is  true,  remains  for 
the  future  to  show.  For  us  the  important  truth  is  that 
here,  as  in  all  other  departments  of  knowledge,  evolution 
proves  to  be  real. 


In  closing  the  present  description  of  the  basis,  nature, 
and  scope  of  the  doctrine  of  evolution.  I  find  great  diffi- 
culty in  choosing  the  right  words  for  a  concise  statement 
of  the  larger  values  and  results  of  this  dei)artment  of 


310  DOCTRINE  OF  EVOLUTION 

science.  So  much  might  be  said,  and  yet  it  is  not  fitting 
for  the  investigator  to  preach  unduly.  The  lessons  of 
the  doctrine  must  be  brought  home  to  each  individual 
through  personal  conviction.  But  because  I  firmly  be- 
lieve in  the  truth  of  the  statement  made  in  the  opening 
pages,  namely,  that  science  and  its  results  are  of  prac- 
tical human  value,  it  is  in  a  sense  my  duty  as  an  advo- 
cate of  evolution  to  make  this  plain. 

The  method  of  science  is  justified  of  its  fruits.  At  the 
very  beginning  we  learned  how,  and  how  only,  sure 
knowledge  can  be  obtained  and  how  it  differs  from  a  be- 
lief which  may  or  may  not  correspond  with  the  truth. 
Based  upon  facts  of  smaller  or  larger  groups,  scientific 
laws  are  so  niany  summaries  of  past  experience,  and  they 
describe  in  concise  conceptual  shorthand  the  manifold 
happenings  of  nature.  Their  difference  from  belief  in- 
heres in  their  ability  to  serve  as  guides  for  everyday  and 
future  experience.  This  entire  volume  is  a  plea  for  the 
employment  of  common-sense  as  we  look  upon  and  in- 
terpret the  world  in  which  we  have  our  places  and  in 
which  we  must  play  our  roles.  Our  search  for  truth  will 
be  rewarded  in  so  far  as  we  organize  our  common-sense 
observations  into  clear  conceptions  of  the  laws  of  na- 
ture's order. 

The  doctrine  of  evolution  enjoins  us  to  learn  the  rules 
of  the  great  game  of  life  which  we  must  play,  as  science 
reveals  them  to  us.  It  is  well  to  remember  that  a  little 
knowledge  is  a  dangerous  thing,  but  because  evolution  is 
true  always  and  everywhere,  an  understanding  of  its 
workings  in  any  department  of  thought  and  life  clears 
the  vision  of  other  realms  of  knowledge  and  action. 
Perhaps  the  greatest  lesson  is  at  the  same  time  the  most 


EVOLUTION  AND  THE  HIGIILR   HUMAN   LIVE     311 

practical  one.  It  is  that,  however  much  we  may  concern 
ourselves  with  ultimate  matters,  our  immediate  duties 
are  here  and  now,  and  we  cannot  escape  them  without 
giving  up  our  right  to  a  place  in  nature.  We  are  taught 
by  science  that  we  live  under  the  control  of  certain  funda- 
mental biological,  social,  and  ethical  laws  ;  we  might  well 
wish  that  they  were  otherwise,  but  having  recognized 
them  we  have  no  recourse  save  to  obey  them.  Evolu- 
tion as  a  complete  doctrine  commands  every  one  to  live 
a  life  of  service  as  full  as  hereditary  endowments  and 
surrounding  circumstances  will  permit.  Tlui>  we  are 
taught  that  the  immediate  problems  of  life  ought  to  con- 
cern us  more  than  questions  as  to  the  ultimate  nature 
of  the  universe  and  of  existence. 

Every  one  can  find  something  worth  while  in  the  les- 
sons of  evolution,  summarized  in  the  foregoing  state- 
ments. The  atheist,  who  declines  to  personify  the  ulti- 
mate powers  of  the  universe,  may,  nevertheless,  find 
direction  for  his  life  in  the  principles  brought  to  light  by 
science.  The  agnostic,  who  doubts  tlie  validity  of  many 
conventional  dicta  that  may  not  seem  well  grounded, 
can  also  find  something  to  beheve  and  to  obey.  Finally, 
the  orthodox  theist  of  whatever  creed  may  discover  co- 
gent reasons  for  many  of  his  beliefs  like  the  Golden  Rule 
previously  accepted  through  convention  ;  and  he  must 
surely  welcome  the  fuller  knowledge  of  their  sound  basis 
in  the  materials  and  results  of  comparative  analytical 
study.  To  every  one,  then,  science  and  evolution  offer 
valuable  principles  of  life,  but  great  as  their  service  has 
been,  their  tasks  are  not  yet  comi-)leted,  and  cannot  be 
completed  until  the  end  of  all  knowledge  and  of  time. 


INDEX 


Achatinellidae,  103,  104. 

Activities,  instinctive  and  reflex,  203, 
205,  208 ;  of  familiar  animals,  208, 
209 ;  differ  from  instinct,  209,  210. 

Adaptation,  universal  relation  to 
en\'ironment,  15  ;  principle  of,  17  ; 
degenerate  forms  enlarge  our  con- 
ception of,  50 ;  results  of  larval 
short  cuts  in  development,  71 ;  109, 
213. 

Africa,  fauna  of,  103,  1G4,  165. 

Agassiz,  a  believer  in  special  crea- 
tion, 98. 

Ages,  Palaeozoic,  92 ;  Mesozoic  or 
Secondary,  93,  94 ;  Cenozoic  or 
Tertiary,  93 ;  Coal  or  Carbonif- 
erous, 94, 

Albumen,  of  egg,  60. 

Alligators,  a  diverging  branch  of 
lizard,  45. 

Amoeba,  21,  51,  69;  comparative 
study  of,  203,  205,  231,  247,  251, 
254,  257,   258,  259,  265,  266. 

Amphibia,  frogs,  salamanders,  a 
lower  class,  45,  62  ;  order  of  evo- 
lution of,  63  ;  evolved  from  fishes, 
64  ;  most  primitive  backboned  ani- 
mals, 92  ;  94,  157  ;  embryos  of,  171  ; 
200. 

Anatomy,  of  mind,  202. 

Ant-bears,  42. 

Anthropoidea,  160. 

Anthropologj',  177;  methods  and 
results  of,  186;  types  of,  186,  187; 
comparative,  of  mind,  211. 

Anthropometry,  177. 

Ants,  communities  of,  125;  mental 
life  of,  207,  208;  organizations  of, 
260,  263,  264. 

Apes,  158;  susceptible  to  training, 
210;  line  from  Ama'ba,  231. 

Appendix,  vermiform,  168. 


Apteryx,  v^-inRlcss  bird  of  New  Zea- 
land, 44,  200. 

Arachnida,  49. 

Archoeopteryx,  a  famous  "link,"  99. 

Ares,  300. 

Armadillo,  42. 

"Arts  of  life,"  226-230;  dwellings  of 
men,  utensils,  227 ;  history  of 
clothing,  228;  arts  of  pleasure, 
228-230. 

Atom,  carbon,  22 ;  nitrogen,  23 ; 
hydrogen,  oxygon,  24 ;  chemical, 
25. 

Atua,  301. 

Azores,  animals  of,  103. 

Bacteria,  amazing  production  of, 
123;  relation  of,  127. 

Baldwin,  148. 

Bandicoot,  42. 

Barnacles,  really  Crustacea,  50. 

Bats,  41,  94. 

"Beagle,"  102,  117,  136. 

Bear,  38,  39. 

Bees,  mental  Ufc  of,  207,  208;  ner- 
vous system  of,  232,  256,  257  ;  or- 
ganizations of,  260,  261,  262; 
queen,  workers,  262,  203. 

Beetles,  67. 

Bernier,  183. 

Bertillon,  183. 

Birds,  44 ;  have  they  descended 
from  gill-breathing  ancestors?  61  ; 
evolution  of.  63 ;  primitive,  99 ; 
embryos  of,  171,  200. 

Blastula,  68. 

Blumcnbach,  183. 

Bonnet,  70. 

Borneo,  164. 

Brachi()iK)ds,  95. 

Brahma.  299,  304. 

Brain,  215,  235-240. 


313 


314 


INDEX 


Brontosaurus,  94. 
Brown-Sequard,  148. 
Buddha,  299. 
Buffon,  114,  135. 
Butterflies,  67,  206,  207,  259. 

Carbohydrate,  23,  24. 

Carbon,  atom,  22 ;   25,  27. 

Carnivora,  35,  37,  38,  39,  40;  order 
of,  157. 

Caterpillar,  larva  of,  259. 

Cats,  Manx,  Angora,  Persian,  37,  39 ; 
domesticated,  137 ;  intelligence  of, 
208,  209. 

Cattle,  products  of  human  selection, 
137 ;  resemblance,  157. 

Cebidae,  true  monkeys,  160,  161,  162. 

Cells,  19,  20,  21 ;  sex,  144 ;  human, 
composition  of,  156 ;  of  ectoderm 
and  endoderm,  255,  256,  257,  258. 

Celts,  218. 

Cercopithecidse,  160,  162. 

Cerebrum,  215. 

Cetacea,  40. 

Chemical  transformation,  17. 

Chick,  development  of,  60,  61. 

Chimpanzee,  163,  164,  195. 

Chromatin,  143,  144. 

Civilization,  a  product  of  evolution, 
272. 

Classes,  32. 

Classification,  32. 

Clifford,  238. 

Coccyx,  168. 

Communities,  cell,  258 ;  insect,  258, 
260-264. 

Comparative  anatomy,  35,  37,  39  ;  any 
form  wiU  disclose  development, 
67 ;  amphibia  evolved  from  fishes, 
64 ;  Law  of  Recapitulation,  66 ; 
insects  arisen  from  wormlike  an- 
cestors, 67  ;  larvae  of  insects,  67  ; 
higher  animals  evolved  from  two-, 
layered  saccular  ancestors,  68 ; 
70,  71 ;  supplements  comparative 
embryology,  72 ;  appearance  of 
great  classes  of  vertebrates,  94 ; 
proves  order  of  evolution,  163. 

Composition,  chemical,  15. 

Compounds,  organic,  29. 

Conger-eel,  123,  124,  127. 

Consanguinity,  essential  likeness,  54. 


Conscience,  287. 

Consciousness,  human,  234,  235. 
Crabs,  48,  49,  66 ;  hermit,  66. 
Crustacea,   lobsters,    crabs,    48,    49 ; 

barnacles,  49,  50 ;  82. 
Cuvier,  158,  78 ;  a  believer  in  special 

creation,  79. 
Curve  of  error,  120. 
Cyclones,  85. 
Cyclostomes,  156. 

Daphnia,  205. 

Darwin,  Charles,  80,  100,  102,  115, 
116,  117;  Origin  of  Species,  116, 
124,  130,  132,  135 ;  Erasmus,  135, 
136,  138,  142,  143. 

Deer,  42 ;  fossil,  of  North  America, 
97,  98. 

Development,  54 ;  a  natural  process, 
56. 

De  Vries,  145,  146 ;  his  mutation 
theory,  147,  148. 

Dinosaurs,  94. 

Distribution,  geographical,  32. 

Dogs,  38,  39 ;  embryo  of,  66 ;  varied 
forms  of,  137 ;  pointer,  sheep-dog, 
instincts  of,  208 ;  intelligence  of, 
208,  209. 

Dubois,  173. 

Ducksbill,  or  Ornithorhynchus,  bot- 
tom of  mammalian  scale,  43. 

Ducksworth,  184. 

Eagle,  44. 

Earthquake,  85. 

Echidna,  bottom  of  mammalian 
scale,  43. 

Ectoderm,  255. 

Egg,  of  common  fowl,  60 ;  of  frog, 
68 ;  nuclei  contains  factors  of 
development,  71 ;  144,  145 ;  hu- 
man, 231. 

Eimer,  148. 

Elements,  chemical,  15. 

Elephant,  41 ;  place  in  zoological 
science,  95  ;  96,  97 ;  age  of,   124. 

Embryo,  of  frog,  58  ;  of  chick,  60-62, 
63,  64,  65 ;  embryos  of  carnivora, 
rodents,  hoofed  animals  alike  in 
earlier  development,  65 ;  of  cat, 
dog,  rat,  sheep,  rabbit,  squirrel, 
cattle,    pig,    65 ;  of    skate,    shark, 


INDEX 


315 


hammerhead,  66;  the  human,  16S, 
170,  171 ;  of  birds,  reptiles,  am- 
phibia, 171  ;  human  hemispheres 
of  brain  like  adult  cat  or  dog, 
215. 

Embryology,  32,  33,  34 ;  of  no  form 
fully  understood,  57 ;  general  prin- 
ciples of,  57-67  ;  embryonic  agree- 
ment, 65  ;  of  insects,  67  ;  weight 
of  facts  of,  69 ;  comparative,  a 
distinct  division  of  zoology,  70, 
71 ;  76,  94,  100 ;  evidence  of,  170 ; 
of  mind,  202,  214  ;  in  early  stages 
of  human,  no  nervous  system 
present,  214 ;  development  of, 
215. 

English  sparrow,  123,  127. 

En\aronment,  111,  112;  influences 
of,  126  ;  determines  mode  of  life 
of  a  race,  213. 

Epoch,  Glacial,  86 ;  Silurian  and 
Devonian,  rich  array  of  types,  93 ; 
Cenozoic,  96. 

Erosion,  89. 

Eskimo,  picture-^Titing,  223. 

Ethics,  281 ;  biological,  283  ;  natural, 
284  ;  evolution  of,  285. 

Ethnology,  177. 

Evolution,  the  Doctrine  of,  1 ;  is  it  a 
science,  3 ;  the  conception  of,  8 ; 
organic,  10-12;  31,  32;  evidence 
of,  54,  95 ;  of  amphibia,  62 ;  of 
birds,  63  ;  of  protozoa,  69 ;  theorj- 
of,  supported  by  palaeontology,  76  ; 
cosmic,  84 ;  biological  evidence  of, 
91 ;  three  important  elements  of, 
109 ;  adaptation,  variation  and 
inheritance,  110;  mechanical,  100; 
dynamics  of,  109 ;  second  element 
of,  122;  human,  150-196;  174; 
physical,  of  man,  falls  into  two 
groups,  153;  of  human  races,  176; 
racial,  177,  178;  mental,  197-240; 
human  faculty  as  a  product  of,  212  ; 
mental  as  real  as  physical,  214 ; 
of  brain,  214-217  ;  of  art  of  writ- 
ing, 223  ;  method  of  mental,  231 ; 
social,  241 ;  of  societies  of  insects, 
258 ;  himian,  biological  interpre- 
tation of,  267-274;  of  higher 
hiaman  life,  278-311;  of  ethics, 
285;  final  conception  of,  307-311. 


Factors,  primary,  secondary,  110; 
three  kinds.  111;  congenital,  113. 

Falls  of  St.  Anthony,  80. 

Fishes,  lowest  among  common  ver- 
tebrates, 46 ;  trunk-fwh,  cow-fish, 
pulT-fish,  mou80-fi.sh,  flounder,  46 ; 
most  jirimitive  barklxjned  nnimalB, 
92;  94;   157;  embryos  of,  171. 

Fiske,  139. 

Flies,  may,  259. 

Flovmder,  a  variant  of  the  fish 
theme,  66. 

Fossilization,  conditions  of,  77-78. 

Fossils.  73-105;  remains  of,  73; 
groups,  77  ;  78,  79 ;  order  of  suc- 
cession, 91  ;  oldest  rocks  devoid 
of,  92  ;  forms,  99. 

Fowl,  game  cock,  138 ;  pigeons,  138. 

Frog,  45 ;  eggs  of,  larva,  develop- 
ment of,  58,  59,  60,  08. 

Galapagos  Islands.  102.  103.  104. 

Galton,  142,  147;  heredity  of  mental 
qualities,  232. 

Gametes,  252. 

Gastrula,  68. 

Gemmules,  143. 

Genera,  32. 

Generation,  spontaneous,  78. 

Geographical  distribution,  32. 

Geological  agencies,  rain,  rivers, 
glaciers,  88 ;  construction,  volca- 
noes, 88. 

Geologj',  data  of,  83,  84. 

Germ,  Bonnet's  idea  of,  70 ;  ccUa, 
144,  146;  plasm,  145,  146. 

Giblx)n,  163. 

Gills,  58,  62. 

Gill-slits,  bars,  clefts,  61,  62,  64; 
in  embryos  of  lizards,  birds,  mam- 
mals, 69;   171. 

Giraffe,  133. 

Glaciers,  alterations  made  by,  87. 

Goats,  157. 

Gorilla.  163,  165,  195. 

Grand  Cafion  of  the  Colorado,  85.  90. 

Gravitation,  155. 

Guinea-pigs,  Brown-S^quard's,  148. 

Gulick,  103. 

Haeckel.  63.  71.  184. 
Hemoglobin,  22. 


316 


INDEX 


Hapalidse,  160. 

Harvey,  70. 

Hawaiian  Islands,  103 ;  snails  of, 
104. 

Heredity,  142 ;  a  real  human  pro- 
cess, 175 ;  instinct  determined  by, 
206 ;  Anglo-Saxon,  213 ;  of  men- 
tal qualities,  232. 

Heron,  44. 

Hesperornis,  99. 

Hippopotamus,  42. 

Hominidse,  160. 

Homo  sapiens,  183. 

Hoofed  animals,  95,  96,  97. 

Hornets,  communities  of,  larvae  of, 
260. 

Horse,  41,  42,  65  ;  place  of  in  zoolog- 
ical science,  95,  96 ;  develop- 
ment of,  97 ;  perfection  of  one 
type  of,  136,  157 ;  167  ;  intelligence 
of,  209. 

House-fly,  eggs  of,  67. 

Human  faculty,  212 ;  its  three  con- 
stituents, 212. 

Huxley,  6,  26,  30,  63,  184. 

Hydra,  50,  51,  52,  53,  68,  69;  com- 
parative study  of,  204,  205,  206; 
254;  cells  of,  255;  256,  257,  258, 
261,  262,  263,  265,  266. 

Hydrogen,  25,  27. 

Hyracotherium,  96. 

Ichthyornis,  99. 

Ichthyosaurus,  9-^. 

Indians,  American,  pictography  of, 
223,  224;  of  BrazU,  227;  life  of, 
272. 

Individual  development,  a  r6sum6 
of  history  of  species,  63. 

Inertia,  155. 

Infant,  human,  activities  of,  216. 

Ingestive  structures,  17. 

Inheritance,  110,  131 ;  biological 
laws  of,  142 ;  paternal  and  mater- 
nal basis  of,  144  ;  145  ;  Mendelian 
phenomena  of,  146 ;  Galton's  Law 
of,  147  ;  laws  of,  in  mental  phenom- 
ena, 203  ;  strength  of,  in  mental 
traits,  232 ;  physical,  provides 
mechanism  of  intellect,  233. 

Insects,  butterflies,  beetles,  bees, 
grasshoppers,     spiders,     scorpions. 


49  ;  66  ;  eggs  of  common  house-fly, 
67 ;  82 ;  nervous  mechanism  of, 
205;  communities  of,  207,  258- 
260-267 ;  nervous  system  of,  256, 
257. 

Instinct,  determined  by  heredity, 
206  ;  of  higher  animals,  208  ;  differs 
from  intelligence  in  degree,  210. 

Intelligence,  203 ;  in  mental  life  of 
communal  insects,  207. 

Invertebrates,  lower  animals  devoid 
of  backbone,  47 ;  structural  plan, 
48 ;  branches  of,  49 ;  groups,  two 
layer  animals,  50 ;  hydra,  sea- 
anemones,  soft-polyps,  50 ;  more 
complicated,  68 ;  palseontological 
materials,  82 ;  evolution  of  lowest 
members,  92. 

Jaguar,  101. 

Jastrow,  294. 

Java,  173. 

Jellyfish,  81. 

Jordan,  David  Starr,  123. 

Kangaroo,  42. 
Keane,  185. 

Lamarck,  115,  133,  135. 

Lampreys,  156. 

Language,  most  important  single 
possession  of  mankind,  218. 

Laplace,  29. 

Larvae,  of  lobster,  66 ;  of  insects, 
67  ;  of  ground  wasp,  207  ;  of  cater- 
pillar, 259  ;  of  wasps,  260. 

Lavoisier,  29. 

Law  of  Recapitulation,  66  ;  stated  by 
Von  Baer  and  Haeckel,  71. 

Lemurs,  158,  160,  161,  195. 

Life,  what  is  it?  27. 

Limestone,  89,  90. 

Links,  99. 

Linnaeus,  79,  158,  183. 

Lions,  101 ;  environment  of,  112. 

Lizard,  nearest  form  to  remote  an- 
cestor, 45. 

Lobsters,  66 ;  larvae  of,  66. 

LyeU,  80,  107,  135,  136. 

MacDougal,  148. 
Madagascar,  161. 
Mallock,  295. 


INDEX 


317 


Malthus.  136. 

Mammalia,  lower  orders  of,  42  ;  their 
own  mode  of  growing  up,  64 ; 
embryos  of,  64  ;  97  ;  members  of 
class  differ,  157.  158;  200;  order 
of  mentality,  203. 

Mammals,  40,  43,  157 ;  embryo  of, 
171. 

Mammoth,  97. 

Marmosets,  161. 

Marquesas,  103. 

Marsupials,  104. 

Mastodon,  97. 

Mechanism,  organic,  14;  living,  110. 

Melanesia,  103. 

Mendel,  Gregor,  145 ;  his  law,  146 ; 
147,  148. 

Mentality,  human,  233. 

Metazoa,  254. 

Mice,  41,  134;  field,  139. 

Miller,  293. 

Mind,  anatomy  of,  202 ;  human, 
differs  only  in  degree,  203 ;  210, 
211  ;  embryology  of,  214;  pala>on- 
tology  of,  217;  and  matter  in- 
separable, 234-237. 

Missing  links,  77. 

Moeritherium,  a  significant  fossil,  97. 

Molecule,  protein,  22,  23,  24. 

Mollusks,  81,  82;  connecting  widely 
separated  ages,  95. 

Monkeys,  158. 

Morgan,  Lloyd,  148. 

Morphology,  32. 

Moths,  67. 

Muller,  293. 

Mutation  theory,  146. 

Naegeli,  143,  148. 

Natural  Selection,  doctrine  of,  116, 
117,  118;  the  struggle  for  exist- 
ence, 124,  125;  simply  trial  and 
error,  131  ;  Darwin  recognized  it 
as  incomplete,  142 ;  germ-plasm 
theory  supplements,  145. 

Nebula,  gaseous,  84. 

Nervous  systems,  201,  202,  205,  200. 
211;  of  worker-bee,  232. 

Niagara,  85,  86,  89. 

Ontogeny,  recapitulates  phylogeny, 
63. 


Orang-outang,  163,  164. 

Orders.  32. 

Organic,  15 ;  systems,  17 ;  transfor- 
mation, analogies  of.  43,  a  real 
and  natural  process,  55,  56,  76 ; 
mechanism,  alteration  of,  55. 

Organisms,  living.  14 ;  analysis  of, 
16;  17,  18,  19.  26,  28.  29.  31.  32; 
characteristic  early  stages,  55;  are 
they  adapted  by  circumstances? 
100;  environment.  Ill;  physical 
heritage  of.  113;  variation  of.  119; 
difference.  121  ;  universal  conflict 
of,  127;  change,  130;  human.  32, 
156,  159,  165-171  ;  nervous  sys- 
tem of,  201  ;  psychical  characteris- 
tics of,  202  ;  many-celled.  257. 

Organs,  16,  17,  28 ;  of  human  body. 
150. 

Origin  of  Si>ecies.  136,  149. 

Origination  of  new  parts,  109. 

Osborn,  148. 

Ostrich,  44. 

Over  production,  122-124,  129. 

Owls,  horned,  of  Arizona,  45;    139. 

Palaeontology,  32,  34,  73,  74.  76; 
evidence  of,  not  complete.  SO.  81  ; 
table  of  facts  of,  91;  94;  second 
division  of  evidence,  95 ;  does  it 
throw  light  on  antiquity  of  man? 
155;  of  mind.  202.  203.  217. 

Paludina,  95. 

Partula^.  103. 

Pearson.  Karl,  6.  7.  142.  147  ;  hered- 
ity of  mental  qualities.  232. 

Penguin,  a  counterpart  of  the  seal,  44. 

Peoples,  fusion  of,  178,  179;  Mexi- 
cans, 178,  181;  Anglo-Saxon.  179; 
American.  179;  Indians,  181,  1S3, 
185,  191,  192;  Patagonian,  ISO. 
192;  Polynesian.  181.  182.  187; 
Moor,  181  ;  Zulu.  ISl,  183  ;  Malay. 
181,  183.  190;  Mongolian,  li>l. 
186-190;  Papuan,  182;  Negro, 
African,  Ethiopian.  182.  183.  192- 
195;  Caucasian.  182.  185-189, 
195;  Veddaha.  182.  188;  Euro- 
pean. 183;  Asiatic.  183;  Lap- 
lander. 183.  190;  ScandinaNian 
types.  Norwegians.  Swedes.  Danc*s. 
Germans  —  uorLb     and     south  — 


318 


INDEX 


186,  187 ;  types  of,  186-196 ;  Per- 
sians, 186,  eastern,  187 ;  Afghans, 
Hindus,  186  ;  Welsh,  French,  Swiss, 
187;  Russians,  187-190;  Poles, 
Armenians,  187 ;  Mediterranean 
type,  Spaniard,  Italian,  Greek, 
Arab,  187 ;  subordinate  group, 
Semitic,  Arab,  Hebrew,  187 ; 
North  African,  Berber,  Hamites, 
187 ;  relatives  of  the  Mediter- 
ranean, Dravidas,  Todas,  Ved- 
dahs,  Ainus,  188;  Manchurian, 
Chukchi,  Buryats,  Yukaghir,  189  ; 
Finlander,  Bulgar,  Magyar,  Ko- 
rean, Japanese,  Gurkhas,  Burmans, 
Annams,  Cochin  Chinese,  Tagals, 
Bisayans,  Hovars,  190 ;  Pueblos, 
Eskimos,  Aztecs,  Mayas,  Caribs, 
191 ;  Yahgan,  Alacaluf,  191  ; 
Papuan,  Australian,  193 ;  Negrito 
section,  Adamans,  Kalanys,  Sakais 
^tas,  Bushmen,  Hottentots, 
Akkas,  194. 

Periods,  Triassic,  Jurassic,  94 ; 
Eocene,  Miocene,  96. 

Phenacodus,  96. 

Phyla,  32. 

Phylogeny,  63. 

Pictography,  223-226;  of  Eskimos, 
of  American  Indians,  223,  224 ;  of 
Asia,  224 ;  of  Egypt,  224,  225. 

Pig,  42,  157. 

Pithecanthropus,  174. 

Plesiosaurus,  94. 

Polynesia,  103,  104. 

Pouched  animals,  kangaroo,  opos- 
sums, 42. 

Primates,  name  given  by  Linnaeus, 
158;  eutheria,  158,  159;  order  of, 
160 ;  anthropoids,  161 ;  arrange- 
ment of  organs,  201. 

Processes,  psychological,  of  higher 
animals,  208,  209. 

Prosimii,  160. 

Proteins,  22,  23,  24. 

Protoplasm,  22-30;  the  physical 
basis  of  life,  143 ;  144 ;  himian, 
156 ;  chemicals  that  make  up,  156. 

Protozoa,  52,  53,  68,  70;  relations 
of,  126. 

Protozoon,  251. 

Psychology,  comparative,  198;  prin- 


ciple of,  199 ;  descriptive,  genetic, 
202;  terms  of,  203;  human,  210, 
211. 

Pseudopodia,  52. 

Pimaa,  101. 

Pupa,  259. 

Pygmy,  195,  196,  227. 

Rabbits,  41,  101 ;  domesticated,  137; 
introduced  into  Australia,  140. 

Races,  human,  age  of,  178 ;  divi- 
sions of,  183-195;  character  of: 
status,  variations  of,  180,  181 ; 
color,  a  criterion  of  racial  relation- 
ship, 181,  184;  hair,  character  of, 
as  means  of  classification,  181, 182 ; 
cranium,  shape  of,  as  means  of 
identification,  nose,  jaws,  182. 

Racoon,  38. 

Rats,  41,  134. 

Reason,  203 ;  in  mental  life  of  com- 
munal insects,  207. 

Religions,  288 ;  Christian,  Hebrew, 
Buddhistic,  Tangaroan,  289,  290; 
Mohammedan,  290,  298;  Dervish, 
Mahdist,  293 ;  linguistic  basis  of, 
293,  294;  of  savagery,  294,  300, 
301 ;  barbarism,  civilization,  294 ; 
elements  of,  295 ;  forms  of  Chris- 
tianity, 296 ;  sects,  Judaism,  297, 
298 ;  Brahmanism,  Buddhism,  298, 
299 ;  Polytheism,  Roman,  300. 

Reptiles,  variations  about  a  central 
theme,  45  ;  lizard,  typical,  46  ;  157 ; 
embryos  of,  171 ;  200. 

Retention  of  better  invention,  109. 

Rhinoceros,  41. 

Rivers,  Mississippi,  86,  89 ;  Hoang- 
ho,  Ganges,  Thames,  87 ;  altera- 
tions made  by,  87. 

Rocks,  crystalline  or  plutonic ;  sedi- 
mentary, 85  ;  eruptive,  88 ;  new, 
59 ;  of  Grand  Canon,  90 ;  testi- 
mony of,  establishes  evolution,  100. 

Salamanders,  45,  46. 

Salts,  of  sodium,  chlorine,  magne- 
sium, potassiimi,  24. 

Samoan  Islands,  103. 

Sandstone,  90. 

Science,  what  is  it?  5,  6;  physio- 
logical, 14. 


INDEX 


319 


Sea  anemones,  68. 

Sea  elephant,  38. 

Seals,  38,  39,  40,  209. 

Selection,  natural,  doctrine  of,  116, 
117,  118;  struggle  for  existence, 
124,  125 ;  simply  trial  and  error, 
131,  136,  artificial,  130,  137,  138; 
laws  of,  in  mental  phenomena,  203. 

Sequence,  physiological,  in  training 
animals,  209  ;   210. 

Series,  sedimentary,  84,  90,  92 ; 
crystalline  or  plutonic,  85 ;  Azoic 
or  ArcheBan,  age  of,  92. 

Shale,  89. 

Shark,  common,  most  fundamental 
form,  46  ;  embryo  of,  hammerhead  ; 
embryos  of,  66. 

Sheep,  157. 

Simiidae,  160,  163. 

Skate,  embryos  of,  66. 

Snails,  45  ;  shells  of,  95  ;  land  snails, 
103 ;  Hawaiian  and  Polynesian, 
104. 

Society  Islands,  103. 

Solar  system,  origin  of,  84. 

Solomon  Islands,  103. 

Species,  origin  of  human,  153. 

Spencer,  Herbert,  8. 

Squirrels,  evolved  from  terrestrial 
rodents,  14 ;  41 ;  flying,  true  ro- 
dents, 41. 

Starch,  24. 

Stephenson,  10. 

Strata,  88,  89 ;  arranged  according 
to  ages,  89  ;  90 ;  time  of  formation, 
92. 

Struggle  for  existence,  124;  intra- 
specific,  125 ;  three  div-isions  of, 
126-129  ;  139,  174,  175. 

Substances,  inorganic,  29. 

Sugar,  23,  24. 

Survival  of  the  fittest,  129. 

Systems,  respiratory,  excretory,  cir- 
culatory, 17 ;  organic,  reproduc- 
tive, 18 ;  nervous,  256,  257 ; 
blood-vascular,  respiratory  and 
excretory,  257 ;  ethical,  286 ;  reli- 
gious, 288. 

Tadpole,  58,  59,  60 ;  larva,  64. 
Tapeworm,     a     relative     of     simple 
worms,  50 ;  123. 


Tapir,  41  ;   MiTritherium,  97. 
Thorndike,   209  ;  heredity  of  mental 

qualities,  232. 
Tidal  waves,  85. 
Tigers,  101. 
Tirawa,  301. 
Tissue-cells,  28. 
Torga,  183. 
Tortoise,  soft  shelled,  of  the  Miaais- 

sippi,  45. 
Tower,  148. 

Transformation,  natural,  170. 
Trilx-s,  32. 

TuV>erculoHi3,  bacillus  of,  127. 
Turtles,  evolution  of,  45. 

Ungulates,  65. 

Uniformitarianism,   Lyell's  doctrine, 

80. 
Urea,  29. 
Ussher,  Archbishop,  178. 

Variation,  110;  cauaes  of,  111; 
among  individuals,  112,  113;  fact 
of  difi'ercnce,  phenomenon  of,  114; 
115,  118,  119,  121.  129  ;  congenital, 
138;  human,  174;  racial,  177; 
laws  of,  in  mental  phenomena,  203  ; 
232. 

Vertebrata,  43. 

Vertebrates,  backboned  animals, 
fishes  the  lowest  order  of,  46; 
principles  of  relationship,  families, 
tribes,  47 ;  53-59 ;  great  classes 
originate  together,  64  ;  more  com- 
plicated, 68 ;  skeleton  remains  of, 
succeed  invertebrates,  92 ;  testi- 
mony of  the  rocks,  93  ;  largest,  94 
appearance  of  great  classes  of,  94 
95;  classes  that  make  up,  156 
lower,  arrangement  of  organs,  201 
nervous  system  of,  256,  257. 

Volcanoes,  88. 

Volvox,  252,  254,  259,  265. 

Von  Baer,  law  of  recapitulation,  71. 

VorticeUa,  251,  252,  265. 

Wagner,  100. 

Wallace,  Alfred  Rusael,  117.  100. 
Walruses,  38. 

Wasps,  ground.  207;  organizatioDB, 
of  digger,  260 ;  201. 


320 


INDEX 


Weismann,  71,  72 ;  proved  nuclei  of 
egg  contains)  essential  factors,  71, 
145,  148. 

Weisner,  143. 

Whales,  40. 

Wilson,  146. 

Woehler,  29. 

Wolf,  Tasmanian,  a  true  marsupial, 
42. 

Wolff,  70. 

Wolves,  140. 

Wombat,  42. 


Wood-frog,  71. 

Woods,  heredity  of  mental  qualities, 

232. 
Worms,  blindworm  of  England,  45 ; 

48,  50,  53,  81 ;  nervous  mechanism 

of,   205,   206 ;  nervous   system  of, 

256,  257. 

Zebras,  96,  97,  112. 

Zoology,    34,    75,    78;    geographical 

distribution,  100. 
"Zoonomia,"  135. 


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ADAMS   LECTURES 


GRAPHICAL  METHODS.  By  Carl  Runge,  Ph.D.,  Professor  of 
Applied  Mathematics  in  the  University  of  Gottingen ;  Kaiser 
Wilhelm  Professor  of  German  History  and  Institutions  for  the 
year  1909-1910.     8vo,  cloth,  pp.  ix  +  148.     Price,  $1.50  net. 

JULIUS   BEER  LECTURES 

SOCIAL  EVOLUTION   AND   POLITICAL  THEORY.     By  Leonard 

T.  HoBHOusE,  Professor  of  Sociology  in  the  University  of  Lon- 
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BLUMENTHAL  LECTURES 

POLITICAL   PROBLEMS    OF   AMERICAN    DEVELOPMENT.     By 

Albert  Shaw,  LL.D.,  Editor  of  the  Beview  of  Beviews.     12mo, 
cloth,  pp.  vii  +  268.     Price,  $1.50  net. 

CONSTITUTIONAL  GOVERNMENT  IN  THE  UNITED  STATES. 

By  WooDROW  Wilson,  LL.D.,  sometime  President  of  Princeton 
University.     12mo,  cloth,  pp.  vii  +  236.     Price,  $1.50  net. 

THE  PRINCIPLES  OF  POLITICS  FROM  THE  VIEWPOINT  OF 
THE  AMERICAN  CITIZEN.  By  Jeremiah  W.  Jenks,  LL.D., 
Professor  of  Government  and  Public  Administration  in  New  York 
University.     12mo,  cloth,  pp.  xviii  +  187.     Price,  $1.50  net. 

THE    COST    OF    OUR    NATIONAL    GOVERNMENT.     By   Henry 

Jones  Ford,  Professor  of  Politics  in  Princeton  University.     12mo, 
cloth,  pp.  XV  +  147.     Price,  $1.50  net. 

THE  BUSINESS  OF  CONGRESS.  By  Hon.  Samuel  W.  McCall, 
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215.     Price,  $1.50  net. 

THOMAS  JEFFERSON:  HIS  PERMANENT  INFLUENCE  ON 
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THE  NATURE  AND  SOURCES  OF  THE  LAW.  By  John  Chip- 
man  Gkav,  LL.I).,  Koyall  I'lofessor  of  Law  in  Harvard  Univer- 
sity.     12ino,  cloth,  i)|>.  xii  -f  8.'>"J.      Trire,  •'?l.r>()  lul. 

WORLD  ORGANIZATION  AS  AFFECTED  BY  THE  NATURE  OF 
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time  American  Ambassador  to  Germany.  12mo,  cloth,  pp.  ix  -f 
211.     rrice,  •SI.-'')*)  mt. 

THE  GENIUS  OF  THE  COMMON  LAW.  By  tlic  Kt.  Hon.  Sm 
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THE  MECHANICS  OF  LAW  MAKING.  By  Colktknay  Ilbert, 
G.C.B.,  CHerk  of  the  House  of  Commons.  12mo,  cloth,  pp.  viii  + 
209.     Price,  §1.50  net. 

HEWITT  LECTURES 

THE  PROBLEM  OF  MONOPOLY.     By  John  Bates  Clark,  LL.D., 

Professor  of  Political  KcoiKjmy,  Columbia  University.  12mo, 
cloth,  pp.  vi  +  128.     Price,  >!l.6b  net. 

POWER.  By  Charles  Edward  Lucke,  Ph.D.,  Professor  of  Me- 
chanical Eniiineerinfr,  Columbia  University.  12mo,  cloth,  pp. 
vii  +  310.     Illustrated.     I'rico.  s2.00  net. 

THE  DOCTRINE  OF  EVOLUTION.  Its  Basis  and  its  Scope.  By 
Henry  Edward  Crampton,  Ph.D.,  Professor  of  Zooloj^',  Colum- 
bia Universitv.     li'mo,  cloth,  ]>]>.  ix  +  .".ll.     Price,  si. 50  ni(. 

MEDIEVAL  STORY  AND  THE  BEGINNINGS  OF  THE  SOCIAL 
IDEALS  OF  ENGLISH-SPEAKING  PEOPLE.  Wy  Wii.mam 
WiTHERLE  Lawrence,  Ph.D.,  Associate  Profei^sor  of  Knjjlish,  Co- 
lumbia Universitv.     12ino.  cloth,  ]ii\  xiv  +  28«).     Price.  $1.5o  net. 

LAW  AND  ITS  ADMINISTRATION.  By  Harlan  F.  Stone, 
LL.D.,  Dean  of  the  School  of  Law,  Columbia  Uuiversity.  12mo, 
cloth,  pp.  vii  +  232.     Price,  §1.50  net. 

JESUP  LECTURES 

LIGHT.  By  Bicrard  C.  Maclaurin,  LL.D.,  Sc.D.,  President  of  the 
Massachusetts  Institute  of  Technolog^y.  12mo,  cloth,  pp.  ix  -|-  251. 
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SCIENTIFIC  FEATURES  OF  MODERN  MEDICINE.  By  FuKDERir 
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sity.     12mo.  cloth,  pp.  vii  -}-  183.     Price,  §1.50  net. 

HEREDITY  AND  SEX.  By  Thomas  Hint  Moroan,  Ph.D.,  Pro- 
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cloth,  pp.  vii  +  284.     Illustrated.     Price,  §1.75  net. 


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FOUR  STAGES  OF  GREEK  RELIGION.  By  Gilbert  Muerat, 
Regius  Professor  of  Greek,  in  the  University  of  Oxford.  8vo, 
cloth,  pp.  223.     Price,  $1.50  net. 

LECTURES  ON  SCIENCE,  PHILOSOPHY  AND  ART.  A  series  of 
twenty-one  lectures  descriptive  in  non-technical  language  of  the 
achievements  in  Science,  Philosophy  and  Art.  8vo,  cloth. 
Price,  i^S.OO  net. 

LECTURES  ON  LITERATURE.  A  series  of  eighteen  lectures  by 
instructors  of  the  University  on  literary  art  and  on  the  great 
literatures  of  the  world,  ancient  and  modern.  8vo,  cloth,  pp. 
viii  +  404.     Price,  $2.00  net. 

GREEK  LITERATURE.  A  series  of  ten  lectures  delivered  at  Colum- 
bia University  by  scholars  from  various  universities.  Svo,  cloth, 
pp.  vii  -1-  306.     Price,  $2.00  net.     The  lectures  are  : 

The   Study   of   Greek  Literature.     By  Paul  Shoret,  Ph.D., 

Professor  of  Greek,  University  of  Chicago. 

Epic  Poetry.     By  Herbert  Weir  Smyth,  Ph.D.,  Eliot  Professor 
of  Greek  Literature,  Harvard  University. 

Lyric  Poetry.     By  Edward  Delavan  Perry,  Ph.D.,  Jay  Pro- 
fessor of  Greek,  Columbia  University. 

Tragedy.     By   James   Rignall    Wheeler,    Ph.D.,   Professor  of 
Greek  Archseology  and  Art,  Columbia  University. 

Comedy.     By  Edward  Capps,  Ph.D.,  Professor  of  Classics,  Prince- 
ton University. 

History.     By  Bernadotte  Perrin,  Ph.D.,  Lampson  Professor  of 
Greek  Literature  and  History,  Yale  University. 

Oratory.     By  Charles  Forster  Smith,  Ph.D.,  Professor  of  Greek 
and  Classical  Philology,  University  of  Wisconsin. 

Philosophy.     By  Frederick  J.  E.    Woodbridge,    Ph.D.,   John- 
sonian Professor  of  Philosophy,  Columbia  University. 

Hellenistic  Literature.     By  Henry  W.  Prescott,  Ph.D.,  Pro- 
fessor of  Classical  Philology,  University  of  Chicago. 

Greek  Influence  on  Roman  Literature.     By  Gonzalez  Lodge, 
Ph.D.,  Professor  of  Latin  and  Greek,  Columbia  University. 


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